Real clouds?
And not the giant fog of bank either. Real clouds that looks real. They can be just a simple 2D layer like we have now, but thicker, but when looking from above or below, they actually look real.
Wings of Prey have clouds 100x better than ours, yet my simple low end gaming rig can run it just fine on max settings.
Jane's WWII Fighters, a 12 year old game, had a mod that made clouds look amazing, and they were just simple 2D layers.
I don't know why HTC can't use the textures and models from these games. They look way, way, WAY better, but the thing is, their flight models are crap. HTC got the flight models down, now it's time for eye candy.
People keep saying "Oh, it'll hurt my FPS", yet how is it that a 12 year old game like Jane's look 10x better. Or how a relatively new game, Wings of Prey, looks SO much better, but still has a low system requirement. My Core2Duo at 2.9Ghz and a Radeon 5570 can max out WoP at 1920x1080. I don't understand why AH can't have better graphics.
It's not going to hurt your FPS, if it does, then you were probably barely able to run this game on the lowest settings in the first place. A simple purchase of a low end card like the 5570 or a nVidia 8800 would make your gaming experience that much better, for the cost of ~$50.