There is a market for simple games which work well cross-platform (minecraft as an example), and there is a market for bleeding edge. The latter, as it stands right now, means DirectX and Windows. More specifically, it means DirectX 10/Vista(well, Win7)+ as many developers (including a very very large developer who shall rename unnamed) are even planning to drop DirectX 9 support on future cross-platform PC titles and instead implement lower-quality OpenGL display for XP and Mac. In the future, pretty things which can't be achieved using SM3-era techniques won't be available even on XP as I'd expect the XP GL implementations to share much of its code with the Mac GL driver and as such not make use of the capabilities of GL3 or 4.
This is particularly true with the push for stereoscopic 3D gaming which, while there is some competition out there, means nVidia 3D Vision/DirectX only. There is 3D Vision Pro for OpenGL on Quadros using quad-buffered stereo, but that is impractical and pretty much requires application support... and good luck with finding games supported well by alternative 3D implementations (even ATI's). Having attended GDC, I saw a huge push for 3D gaming. And TBH, it's warranted.. the effect is awesome. Personally, I hate 3D movies as they give me a headache, but the ability to tweak the convergence point and depth of stereoscopic 3D with a realtime-rendered viewport to your comfort level puts it right in that sweet spot.
I think the fact is that gaming in general just continues to grow. Gamers love Angry Birds (though I can't figure out why) and Farmville (this one eludes me even moreso), but gamers also love Battlefield and Crysis. It's expensive to develop a bleeding edge game, equivalent to the cost of producing a summer blockbuster, yet developers continue to do so because it's a good investment.
I'd be happy to see the latest hardware and games work well on alternative platforms, but it's not a reality at the moment. With Apple steadfastly refusing to allow 3rd party video drivers, while keeping the system OpenGL locked at 2.1ish (with some proprietary extensions), that just isn't going to happen soon. Linux at present isn't even worth mentioning as a gaming platform and seems unlikely ever to be. When you're talking about gamers who invest hundreds on just their video cards, dropping the cash on a Windows upgrade is a non-issue. Windows just works, with top level support for the latest hardware.
Fact is the next generation of consoles are years away. Game developers do not have even preliminary specs from the manufacturers and are even questioning whether it'll happen, or if we'll see something else which moves more toward a unified entertainment platform. Until that happens, the consoles will be in a state of "3+ years away" and never getting closer. Then when they do come out, it'll be 1-2 years before anyone but the hardcore console gamers even bother with the systems due to cost.
Anyway, I share your belief that this is could be the last generation of consoles. And to that I say, good riddance. I'm playing Dragon Age 2 right now and while it's a great game, the clearly-designed-for-clumsy-controllers interface is an annoyance. I have a mouse with a scroll wheel, I have a keyboard, and I have a screen that has been capable of higher than 720 vertical scan lines for the past 20 years. Anyway..