That's precisely the point though, the ending is a foundation upon which we can project our own ideas - it's not there to expound on every possible outcome and ripple. The implications and consequences of a given situation are different under each person's interpretation (and their Shepherd's actions and intentions). You and I each take it to mean different things and conclude different things. Attempting to create an ending that encompassed everything would torch that (which I think is a bad thing) and be monumentally complicated and long. Not to mention doing something like that has a tendency to create a "canon" ending which can be a difficult precedent to work around moving forward - even with such an open-ended finale we're still seeing ME4 attempt to distance itself from 1-3 so that it's not hemmed in by them.
Endings open to interpretation are fine, my point is ME3's endings are almost completely unrelated to the story. The games should have properly prepared the player to make that final decision. Instead we got a character-based space opera that tried to turn into a completely different genre on the last page. Themes of control, destruction, and synergy should have been explored via the plot in at least some detail, and frankly they weren't. Sure there was the occasional moral choice that lightly touched on some (not all) of those themes, but it was always in the context of "the best solution to the immediate problem".
Take the movie Inception. The ending with the spinning top is notoriously open to interpretation, but no one gets pissed off because the plot provides enough information about its notions of dreams for the audience to come up with their own interpretations. In fact the entire movie is about interpretation of dreams and how real they are (or not). It makes sense that the ending should be about that as well.
Now imagine if at the end of any given episode of Star Trek, Picard suddenly asks Riker into his ready room, presents a top, tells Riker that if he spins it and it falls, it's reality. If it doesn't stop, it's a dream. Nothing about this top has ever been mentioned before, and it has no relationship to the episode in question. Then they spin the top, and the episode ends. That's what the ME3 endings are like to me and many others.
AI's cannot rationalize. It's simply a conclusion it came to which it claims is supported by observation (over the course of 'countless' Reaper cycles and whatever it observed pre-Reapers as well). It could just be a front but most of the information in the game corroborates the Catalyst's story in terms of synthetic/organic relations and the length of the Reaper's/Catalyst's existence.
The reconciliation between Geth and Quarian is promising - to "us". But again the scale of the Catalyst's existence needs to be taken into consideration. Is one conflict reaching peace out of how many (presumably) hundreds or thousands of failures to do so really statistically significant? It's an outlier. Not to mention the simple fact they were at war to begin with and the extraordinary circumstances required to reach peace weakens the case even more. Further I think the Catalyst would likely attribute it more to Shepherd than anything else - Shepherd him/herself is an anomaly which has made this harvest cycle different. Shepherd is perceived as a threat because he/she seemingly wields the power/influence to de-rail expected results.
At the very least the catalyst is clearly making judgments based on incomplete/bad information. The presence of Shepard alone does threaten to de-rail expected results, and that's the problem. Shepard may be the first organic to reach the catalyst, but he's hardly the first person to have singularly unique effects on history. From our own history alone we have countless individuals who have changed the course of civilization by mere force of personality. If Stalin didn't exist we probably don't have a cold War, or at least we have a very different one. If Hitler didn't exist, there's probably never a 3rd Reich. And that's just two people in our single species, over a single century.
Outliers are not to be discounted. It's quite possible that Synthetic/Organic peace is an outlier, maybe even a combination of outliers. That does not make it impossible or unworthy of pursuit. The fact the catalyst makes this basic fallacy leads me to believe it's full of shit, particularly given it's mission to preserve Organic life. It's quite arguably that peace with synthetics is the ideal preservation.
You can see that in the Geth themselves. Sure they were technically "at war" with the Quarians, but until Sovereign came along they were just chilling out in the veil in their conquered territory. Likewise there were multiple factions among the Geth, some who favored peace with organics. And sure enough peace was possible.
I don't trust the Catalyst. Its conclusions seem to fall apart or at least be severely debatable upon even basic analysis. The fact that it's really really old and probably has more information lends it no more credibility than my 70 year old Tea Party relatives. Idiots can have access to a library and still be idiots, even if they have smart parents, and especially if their programming makes them that way as appears to be the case with the catalyst.
Given the choice I'd have it show me the data, subject that data to intense independent analysis from all species in the galaxy and justify it's conclusions before accepting the 3 "options" it provides. The reapers could stand down in the meantime, since we're not supposed to be able to defeat them anyway.
I agree that 'synthetic v organic' is really just an extension of 'creator vs created' (or controller vs controlled) conflicts. And that's actually part of the reason I don't think the reapers (eg: Sovereign, Harbinger) are actually sentient individuals. I think the Catalyst recognizes the threat Reapers could pose to it (or perhaps more appropriately: the threat it could pose to the Catalyst's 'mission') if they were capable of questioning why they serve the Catalyst - and would construct/program them in such a way that would preclude that possibility. Because of that I think the Reapers are simply programmed to seem sentient to make them more menacing/able to interact with the organics if needed. But they're actually driven by a "VI" of sorts or maybe some sort of cut-down version of the Catalyst itself. Or maybe the Catalyst has direct control of all of them all at once - probably not - but it could be possible. Regardless, I don't think the Reapers are self-aware.
It's stated that the Reapers are preservations of previous sentient species, down to their consciousness. That implies some level of self-awareness, given that the physical forms are clearly destroyed/melted down. That or the Catalyst has it's own bizarre definition of "preservation" that doesn't really preserve anything meaningful beyond knowledge. Would fit well with the rest of its irrationality.
I think the implication that the writers were going for is that the Repears are willing participants, because when you sum up the consciousness of millenia of sentient species from countless reaper cycles, that consciousness realized the necessity of the cycle and become complicit. If that's the case, I think the writers could use some antidepressants.
Fair points, though I don't know that the cities are quite so decimated. The industrial areas, iirc, were targeted quickly and early but when you fight on inhabited planets throughout the game (you could also maybe take some of the combat maps from multiplayer into consideration) most of them show quite a bit of infrastructure/buildings still intact - probably residential.
Travel between multiple solar systems would probably still be very slow without the Relays but at some point the Relays and Citadel were discovered without actually using them first so it's not as though travel beyond one's own solar system is out of the question entirely. Moreso it's just much less efficient. I don't think we know enough about Thessia/Palaven/Salarian homeworld to really know how they'd fare but on Earth things would be difficult no doubt. While Earth was experiencing a period of revitalization (prior to the invasion) due to injections of resources and technology from colonies/trade thosewould now be mostly cutoff. But it's also already received enough of them to at least start repairing damage caused in the 21st century (lol). There would probably still be widespread famine depending on the state of agriculture and it's ability to support billions of people without aid though. But it's not like they're dressed in rags living in caves.
http://masseffect.wikia.com/wiki/Codex/The_Reaper_War
After destroying Earth's comm buoys, smaller Reaper destroyers wiped out all GPS and communications satellites in Earth's orbit and cut the undersea fiber-optic cables that linked the continents. Earth's resistance now relies on outdated radio towers and a few quantum entanglement communicators whose matched pairs happen to be on other continents or outside the Sol system. Communication is so limited that the fate of entire nations remains unknown.
The capital ships bombarded defense installations and industrial centers, annihilating entire cities with populations in the low millions, including Adelaide, Hamburg, Al Jubail, and Fort Worth. Meanwhile, Reaper destroyers descended into the atmosphere to melt roads and capture population centers with minimal loss of life. This is not an example of the Reapers being merciful. More likely, they are herding their prey to make the coming harvest that much easier.
http://masseffect.wikia.com/wiki/Codex/The_Reapers
The rate of killing is phenomenal. Intelligence estimates suggest there are more than 400 processor ships on Earth, killing approximately 1.86 million humans per day. In combination with battlefield deaths, disease, and famine, this pace will result in the complete depopulation of Earth within a decade. As the husks and indoctrinated slaves build more slaughtering facilities, the kill rate can only increase.
As for other planets:
The Reapers countered instantly. Their destroyers performed a jump of their own to the skies above Palaven, beginning orbital strikes on turian cities. The turians, forced to defend the planet, found themselves in a pitched battle far from the relay, from which emerged a seemingly endless line of Reaper ships. After massive casualties, Coronati ordered retreat.
The turians insist that Palaven is not lost--the battle has merely moved to the ground. Reaper troop transports have dumped hordes of husks to capture Palaven's inhabitants, but met with little success. Reaper capital ships are destroying city after city. But much of the turian fleet is still operable, and the citizenry is heavily armed. The turians refuse to be intimidated.
Unfortunately, the Reapers' greater numbers allowed them to accept certain losses, so they soon ignored the attacks against them and began orbital bombardment of Thessia. This in turn forced the asari to defend their homeworld with a more traditional stance, facing the Reaper forces directly. As soon as the Reapers landed on Thessia, the harvesting began.
A swift and brutal slaughter of the asari ground forces followed. Resistance from trained biotics barely slowed the attackers down. In the end, Thessia's minimal military forces, combined with unpreparedness in the face of an overwhelming enemy, resulted in the fall of the planet.
Sounds pretty devastating to me. Even if FTL is still possible, all of the ships in that last battle have to be seriously damaged and the Reapers have certainly destroyed any shipyards. I'm not saying it would be impossible to rebuild, just that there's likely to be a fairly long dark age regardless.