The only thing I wanted to point out with a lot of work and a maybe not so good example is that your equation (your point 1.) is wrong as you initially put it.
A market for a massive-multiplayer-game like WoW
CAN never be the goal for a game that was originally intended for an offline-game with multiplayer-ability. Just as a tactical shooter like Rainbow6 can never compete with games like Quake and Unreal, though these genres are a lot closer related than Roleplaying and Flightsimulation. Any trial to create a chimera of both is doomed to fail (RB6 Lockdown/Vegas, for example).
As you posted, Flightsims are a niche-product. That's not as bad as you may think, though, considering that UBI saw the potential of IL2 pretty soon and secured their rights on the SoW-Engine.