Actually it is slighly more advanced than "diablo" was when it comes to procedural generation. Yes, the area between the 90m points is generated randomly but it is not consistantly different. A divit or lump in the grass will be there every single time you go to that generated area 100% of the time. UNLESS you modify the terrain with the road editor or drive a car over it(soon) or create a runway over it. Then an additinal terrain file is saved with the changes and loaded. Should at some point you remove those features the ground will return back to its original state.
25,000 airports, No not unless you and the community are willing to make them. I wouldn't hold your breath for any of the "big" companies to buy in and add them for you either. All the tools required will be given to you and new tools are being added as they are suggested.
AI aircraft.. No ai of any sort YET but it has been discussed for other aspects as well, Animals, Ground Vehicles, AI workers
ATC.. Well I imagine this would need to be arranged as an addon by a flight sim community. OT in any form will be not just mod friendly but mod dependent.
Real world Weather.. Not Yet! but then again there are no clouds yet and nobody seems to notice.
etc.. yes. Has pleanty.