I was discussing this with a friend the other day, it's a little hard to explain but I'll try my best. It would be an MMO* in that it would encompass so many different genres, some people would log on to play a space combat and construction game across whole galaxies, directing fleets and planets.
The next group would be ship commanders and planetary commanders, the former would be in charge of transportation and combat situations, the latter playing an RTS Style game where they had power over a planet and selected where cities were to be built, and directing smaller groups- militairy commanders could play a tactical style game and others could follow out these orders in a first person shooter.
Really the avenues are endless, anything from driving games to hacking games could be incorporated into this.

Obviously there would be problems- Deciding who gets to play what position, whether people are 'promoted' from the ground levels up to the commanding positions by the amount of time they spend on the game or their skill level, or what happens when there aren't enough soldiers for the tactical commander to work, online games can be very fluid and unpredictable.

EVE Online?

EDIT: Actually your idea sounds like a multiplayer version of Battlecruiser 3000, which sucked ass. Maybe you could have better luck...

its already difficult to create an interesting game for single player that incorporates all genres, but its near impossible to do it as an MMO, and make it interesting for all the genres.

the problem with games that try to try to be epic by incorporating something that has never been done before is that they ONLY focus and try to exploit this new idea, and leave out the fundamental aspects that make games good

Yeah, he basically described Alliance-level play in Eve.

If the best place you can put forth your idea is TOTSE, it's not going to be made (or already has been.)

So new ideas aren't welcome if they don't have the sure chance of becoming a reality?

Bummer.