I guess I'm confused on how having DX10 applications will take away from a TH2G resolution. Perhaps I am just not in on all the subtleties involved?
From my small experiences, if a game supports widescreen natively, it will usually support TH2G resolutions natively as well. A good example would be
Genesis: Rising. The game natively supports TH2G, but well... the game is ugly and the mouse movement is linked to the screen in a 1:1 correspondence, so as the screen becomes extended to fit the extra monitors. Mouse movement becomes more exaggerated and unwieldy. Perhaps I will make a detailed report on it. But after playing it surround for only a hour, I had a severe headache and switched it back to 4:3 (definitely improved playability for me).
That was a rather long winded way of saying that there is more "support" for TH2G than we realize. Once you break the mold, and have developers thinking about adjusting their displays for different aspect ratios, to say "while we are at it, why don't we just allow the game to display whatever the monitor supports?"