HTC knows that kind of system specs they need to have. They're the ones with the market research guys.
They're NOT going to cater AH2 to those few people (a vocal few for sure) who constantly upgrade so as to have the fastest PC available. Remember that to ensure constant growth, HTC needs to appeal to the largest possible user base--eliminating much of that base by having "harcore gamer"-level system specs would be contrary to that goal. In the end, graphics are good for little more than screenshots...it is the GAMEPLAY which will make or break the game, not the eye candy.
At best, those of you with ultra-fast (2 gig +) systems should hope that various levels of graphic detail are supported in AH2. This would IMO be a wise feature for HTC to implement, since it would effectively provide AH2 with a built-in way of keeping up with people as they upgrade their systems.
That said, I wouldn't worry about the appearance of AH2. Even now, the current version of the game looks fine--the new version will doubtlessly be a big improvement. In a flightsim, the item most important for graphics/immersion is ground detail and terrain, which has already been noted by HTC as being much improved in AH2.
J_A_B