The multi-client persistant universe game could easily be the future of gaming. No other type of game could possibly bring in as many players as a game like that. But why stop at three clients? The game universe could house every kind of game all at the same time. All of the online sports games could exist in this world, as could racing games, first person shooters. Even a family client such as The Sims could live in the multi client world.
When your RPG character visits the Pod Racer track, he would be seeing races run by real people. If you break into a house for a little random theivery, you could be breaking into the house of someone using the family simulator client. The possiblities are endless.
Look over your game collection. I have looked over mine. Almost all games could be integrated into this new combined universe, Sim Farm, Dungeon Keeper, Mechwarrior, you could probably even manage to integrate games like Who wants to be a Millionaire, and all of the various Las Vegas games. Online gaming could finally have some semblance of true reality. A game where everything is real, everything is player controlled. That is the future. The company that does it is going to own the online gaming market for years to come.