DX11 has a tough road ahead. It is definately the future and a welcome change, but i doubt we see any full DX11 titles for a few years yet.
There are two things that need to happen before you see mainstream games make full use of DX11:
1) Next-gen consoles that run DX11. Consoles are the dominant force in game development. Most games start out on the console and then are ported to PC. Consoles still run DX9-ish so most people make full use of this.
2) A large percentage of users who have DX11 at the INTEGRATED graphics level. You will never see truely mainstream games like Sims or WoW go DX11 until everyone with a 5year old bargain PC can run it.
DX10 is starting to see some use because it is just eye-candy. DX10 has nothing that will break a game when used on DX9. A DX10 game on DX9 hardware: bummer, the water doesnt look as nice, or the clothes arent as cool, or the explosion wasn't as real, but the water, clothes and explosions are still there.
DX11 has so many departures from older DX's that it is not just eye-candy that can be turned on and off. DX11 brings about whole new ways of building game engines that will be so engrained that you must have completely different engines and logic paths if you make full use of DX11 until it becomes the norm and you can code exclusively for DX11.
Who knows what can be accomplished with tess. and compute shaders. Whole logic systems and AI could be built into the CS and would not even run on the non DX11 hardware, forcing the huge re-coding.
Something DX11 has that DX10 did not, is the performance advantage and the Windows 7 advantage. DX11 (as well as ATi's DX10.1) will allow better performance for sweet features rather than DX10's 'I think i see the difference, but OMGz i just lost half my FPS'. Also, there are still people holding out on XP machines that hate Vista with a passion that will finally be won over by Windows 7. I am one of those. I ran win 2k until XP SP2 came out, and now that I have been running Win7 RC1 for some time, i will jump on 7 when it comes out.
If DX11 was to take over fast, it would require that ATi stop shipping any non-DX11 parts and go DX11 exclusive from integrated to the high end. Intel would have to make their integrated DX11 compatable (they have what, over 50% of the market?) and Nvidia would have to speed things up. Its great that ATi will have DX11 parts before DX11 is even released, but like others have said, there will be no big hurry for it. Perhaps this is why ATi is making such a stink of Eyefinity. There has to be something that people want NOW and can use on CURRENT games to enhance their experience.
Eyefinity IS cool and can be used NOW, but it will also take 58xx level hardware to push those kinds of megapixels. This is another reason why ATi is in no real hurry to get sub 58xx level hardware out.
-Plack