Last generation (Z170 in particular) had SATAe on essentially every board from every manufacturer. That Gigabyte only has it on three is a sign of diminishing implementations.
That seriously sounds like a complete guess. How many motherboards had SATA Express at launch? How many AM4 motherboards are out there now for a lunch platform? Do you believe every motherboard following this AM4 launch will be feature parity with existing boards throughout the service life? You're taking a bunch of observations (new platform, new CPUs, new chipset, new designs) and saying that it's diminishing, which it is, but you provide complete conjecture as to *why* its diminishing. That also includes the fact that you seem to think it has some sort of "permanence" about it. Samsung SSD shipments were down Q1 2016, but no one considered it permanent. And it wasn't.
While I agree with you in theory, the practical end result is that it's nearly impossible to make a NVMe drive for PCIe x2 that couldn't possibly benefit from x4, and the controller and development cost is pretty much identical. As such, all drives going forward are made with an x4 interface, and thus will never get SATAe connectors as those would place an artificial limitation on drive performance.
Again, complete conjecture, and absolutely wrong. Companies like JMICRON have already noted scrapping x4 PCIe controllers in exchange for x2 controllers to hit price points.
Also, you've got your numbers wrong. SATAe is two SATA ports or two lanes of PCIe 2.0/3.0, allowing for a single drive to use these lanes. If you're talking about the common dual SATAe connector blocks, those have four SATA ports, two independent SATAe ports, and the use of one SATAe doesn't affect the availability of the other SATA ports.
My numbers aren't wrong, but I could see the mis-interpretations. In my original post, I was discussing AM4, because AMD is implementing SATA Express on Chipset. In that area, reviewers have noted that the 2 SATA Express Ports can be divided into SATA, used as 2 x2 PCIe NVMe ports, or coalesced into an x4 PCIe port, hence why it can also be another M.2 slot.
It might be conjecture, but it's supported by pretty much every tech writer in the world. The added cost of a PCIe controller pretty much necessitates an x4 interface to eke out as much performance as possible to recoup as much of the development cost as possible. This applies whether the drive is meant for low-end or high-end applications. Besides, Intel is already making the 600p, which is barely more expensive than SATA SDDs. As such, there is no logical reason to go for the in-between solution of an x2 interface - either go whole hog x4, or SATA with the significant cost savings this brings with it. There is definitely a market for low-end NVMe drives, just like there is a market for high-end SATA drives. I just don't see any reason to gimp these drives with an x2 interface that will further limit their performance.
Again, as you noted, it's conjecture. You have provided no evidence, while I have provided evidence indicating the opposite:
http://www.anandtech.com/show/9369/...-sata-6gbps-jmf815-pcie-controllers-next-year
Controllers stay on process nodes a very long time due to cost reasons. Even after the jump to 28nm, it still doesn't necessarily mean there aren't room for x2 controllers. You're welcome to bring conjecture if you want, but stating it as some sort of fact is silly.
EDIT: Noting that @cbn posted this information ahead of me. I made this post in my spare time over 3 hours, so I missed it.
I'm not saying it's impossible that a pure SATAe drive will appear at some point. I'm just saying that based on three simple facts - that manufacturers have abandoned/canceled all known SATAe device development, motherboard manufacturers are moving away from the standard, and there's no extra cost involved in using m.2/u.2 instead - there's no reason to suspect this will ever happen.
To the first point, that's fine. Again, SATA Express does not require devices be made for the interface to live.
To the second, a single brand new platform launch does not a trend make. Since you said "facts", can you bring any evidence forward with any numbers that shows SATA Express is releasing on fewer motherboards within stable platforms? Or is this more of an observation?
As for rational arguments against SATAe: it adds board complexity, it's a horribly designed connector (seriously, that thing is awful), and device manufacturers have shown no desire to utilize it.
Again, compared to what. You have yet to provide a valid alternative. It adds board complexity? How? AM4 leaves it entirely up to the OEM. They could not implement it at all, or they could make additional SATA ports. Or they could even make the block a x4 PCIe slot, or hell, make it an M.2 slot. The idea behind AM4's implementation is that it gives the OEM total freedom on the final implementation
without the complexity of having to add an additional controller to the motherboard. How can M.2 help with that? How can U.2 help with that? Why do you think that space constricted M.2 slots do not add to board complexity when you have to route a slot, and make sure no components interfere with the M.2 card that ends up mounted on he motherboard. Seriously, that doesn't make any sense. As for the connector, compared to what? M.2 only has a kludge of a connector. U.2 carries 2 channels as well but is a much more robust cable, SFF-8639. The cables are individually shielded! Have you ever bought Mini HD SAS cables? Are you aware of how much those things cost right now?
I would love a way to easily hook up x2 PCIe over a cable - that has a million possible use cases. The problem is that SATAe is a bad solution to this problem. While its innate flexibility is nice in principle, in practice it makes for a huge, ungainly and impractical connector with a nightmarish cable. U.2 takes up less board space, does more, and its size makes whether or not users use them just as moot a point as with the SATAe connector. The ideal way to solve this would be u.2 ports with support for lane splitting. Much, much more convenient than SATAe.
I would love that too. Lots of uses. But we don't have it. The rest is simply an opinion which I can't agree with. U.2 takes less board space as a connector, but gives up flexibility. It's entirely personal opinion on which you would rather have. I agree the SATA Express cable is therefore much larger, but that's a trade-off. Do you think people will want to spend $40 on what's essentially a SAS3 cable? We can't even get people to spend more than $70 on their power supplies a great deal of the time.
U.2 lane splitting already exists, because it's primarily a commercial product designed for Enterpise use. Dual Port U.2 drives like the Intel DC3600 have been on the market for a year now. But they go many to one, rather than the many to many you're wanting. That's because U.2 either sends 4x PCIe for 1 controller, or 2, 2x PCIe for dual controller mode. Unlike SATA Express, all of the lanes are sent down each U.2 connector to each device. How would you do what you wanted? Would you go back to the days of master / slave drives where you manually set each drive, or use a separate cable that only had half the lanes in each U.2 connector? That standard doesn't exist by the way. You'd have to create a whole new SFF cable standard. And even when you
did achieve that, you'd end up with
2, 2x PCI-e connectors. That seems like a lot of work for something we already have though. It's called SATA Express
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