I don't know how much of this game is planned at the moment, but I'm wondering if there'll be much room for exploration in this game.
There might not be much scope for interacting with the environment - obstacles might just be a nuisance for top down flying - but as the game is currently said to be set in the upper atmosphere Arcen could easily fill the background with beautifully drawn scenery for us to fly over. For all that AE is going to have to focus on blowing stuff up and sticking stuff together, it would be a huge bonus to be able to search worlds for new vistas to gaze over.
This might just be me (I'd play anything that looks and sounds pretty enough, almost regardless of the rest of the game), but think: if it looks good enough then we'd have something to point to whenever the seemingly inevitable 'Arcen have crap artwork' comments turn up.
On a side not, there could be some basic environmental effects that could be easy enough to add - engines could run worse in hot climates (deserts etc.), wind currents, stuff like that. I'm not sure much could be added along those lines without creating more work than Arcen need though.