IL-2 won't die till there's enough content out there for SoW, as for IL-2 making it to 4.12 and beyond, it depends on how motivated the voulinteers are once SoW comes out, i suspect they'll stop making the patches and start making stuff for SoW, and we might see 4.11b1m or something
and i doubt we'll ever see another flight sim engine thats specifically designed just for air combat(at the quality of SoW/IL2), we'll probably only see total war sims from now on, ground, air, sea, and in futuristic games, space, all in one simulation, just because their so darn expensive to produce at this quality, the only way to make it affordable is to make it open enough that it suits as many genres as possible, and 10 years down the road computers will be so fast that games like SoW will look to us then, like those screenshots in the earlier posts do to us now, and we'll be wondering why we ever played something that was so limited. don't forget moors law, and advances in not just cpu speed but peripherals, new screens, higher resolutions, even stuff like true 3D (not with stupid glasses) are all highly possible within the next 10 years

anyway, the main thing to remember is that 10 years is a long time, and if you look at our advances in the past 10 years, you can clearly see that games of all genres have gone from near stick figures and plastered on textures, to highly dynamic multi-textured, high polygon tesselated, near real looking characters, hell even 5 years ago game engines couldn't render round wheels well, they were just like decagons.