You know, I actually WANT a WW-III simulation.
The cold war is over, so it's not going to ruffle any feathers to have a simulation about that war that never took place. It would probably work Online too since I doubt now there would be a lot of loyalty to the NATO side of the conflict, while only two players join the Soviet side. Both sides would probably have a sufficient player base.
I would set it in the 1950s and '60s. You know, before fire and forget missles were finnally living up to their marketing hype. I want to use piloting skill and not rely on the missles.
The Century series of US fighters, French Mirages, MiGs, Sukhoi's. The Russian planes of that era are just as good, or better than the western ones, so that might also attract the players to join the Red side. Would you rather have a Mig-21 or a F-102 Delta Dagger (which was never a really good plane)?
Carriers with steam catapults and angled landing decks, In-flight refueling AI aircraft, AI radar picket planes, hell....use nuclear bombs as a daily weapon, not a rare weapon. It is all about who can nuke more cities. Also, there are SAMs to deal with from the AIs, and Wild Weasle missions in the reverse.
Two seater fighters, with both stations modeled. You need to jump between them to operate the radar or fly. Or take a Weapons Officer with you.
There is a lot to be had in a WW-III flight simulation.