I'm bored so I'll jump back into this never ending discussion.
1: The Wii is selling to the same demographic the DS is: children ages 8-14. Well, technically not to them - their parents are the one buying the consoles - but that is the majority on the console. Before you get on my ass about being a 30 year old married man who owns both a DS and Wii - that is fine, they aren't ONLY being sold to kids. And they do have some games that are great. But the 8-14 market is so insanely huge. Games for that market are also cheap and easy to make. A 10 year old isn't the best video game critic. The DS was great in its on-the-go simplicity to quell kids in the car or when taking them out someplace. I dare to you find a kid that age in "middle America" who doesn't own at least one (it's usually 1-per-kid). The Wii is riding that same simplicity wave in the living room - allowing anyone to jump in and play regardless of age or maturity level. It's been said a lot, but really, it's not "for us".
2: The PS3 is, for the vast majority, seen as an HD-only system. I know it doesn't have to be, but that's how it is. HDTV sales are increasing, but they haven't caught fire. Part of it is the current economy, part of it is the lack of real HD standards and increased fees for a moderate amount of HD content from Cable and Satellite companies. Blu-ray is growing, but it's nowhere near DVDs. Since DVDs were so huge (and the DVD market really is HUGE) - many of the people who bought DVDs are less likely to buy a Blu-ray for the same movie - this unlike the VHS-to-DVD conversion, where the obvious benefits outweighed the costs (no fast forwarding alone made it worth it). We're just getting TV into the entirely digital realm - it will be quite a while (10 years, if ever?) before we get into the entirely HD realm.
3: Compare the top selling-points of the 360 and PS3.
360 has Xbox Live (a pay service), standardized everything (achievements, friends, voice, etc), and Halo. Yes, I would say Halo is a top feature of the 360. No, I don't like the game much, but something like 9 million people do. And you can get the console for $200 (bundled with games).
PS3 has Blu-ray - without a doubt the biggest selling point of the console. Again, I'm sure you will say "I love my PS3 and don't even care about Blu-ray!" That is fine. You aren't the majority. The PS3 also has the Playstation name - something you cannot argue Microsoft has anything close with the Xbox name (but that has changed a bit with the 360). And I would say the 3rd thing the PS3 has is the hardware reliability factor. Though this is more a 360 failure than a PS3 success. And you can get it for $400 (bundled with a game?).
Notice the difference? The Microsoft console, though built out of paper-mache, has its strengths built around games and the gaming platform. The PS3 has strengths in brand and HD movies.
Now that Blu-ray players can be had for $200 and falling, the PS3 needs a lot to even remotely have a chance at "2nd place". First and foremost is a sub $300 price tag (no, Sony credit card discounts don't count), though they simply can't do it because they're still losing money hand-over-fist on the system. Second, they need a home-run first-party title. God of War is barely on the radar for a 2009 release. Gran Turismo is 2010? LBP was a critical success, but that didn't translate into big-time sales (it's on par with MGS - which is very similar to Fable 2 numbers, to give some 360/PS3 exclusive comparisons).
With the 360 so far ahead at this point, and word-of-mouth and "buying the system my friends have" such an intricate part to a console's life - the PS3 can't catch up. Is the PS3 a sinking ship? Hardly. Will it "finish 3rd" this generation? I'm confident it will. By a larger margin than most think - particularly in America.
I'm just genuinely curious to see what Sony does in 3 years - when they still have a trailing console that just turned profitable but the other 2 manufacturers are getting ready to release the new generation. This might be a longshot, but it could very well be that Sony stays true to the 10-year PS3 lifespan they've projected and skips the next generation altogether - though the "next generation" could just be an advancement that we've been used to seeing in handhelds rather than consoles (think Gameboy to Gameboy Color) - MS and Nintendo to release slight improvements of old hardware with new functionality - keeps the division profitable but still allows for growth - cheaper to manufacture.
Just pulling stuff out of my butt.
Ok, I'm done.