The game idea sounds pretty damn good, especially the realms part.... because I may want play a futuristic galactic FPS game and traverse the planet with awesome vehicles, or just go medievil and journy the planet to slay dragons... Problem is I would think its mammoth tasks and would take years! scratch that... Decades maybe...
For an initial release candidate game... I think something fairly simple should be order, something that will be quick to make and impliment, just to show the potential it has, kinda like a techdemo in the form of a small game... Let actual devs work on full scale games to push your engine to the max, that way you can spend more time improving and supporting the engine, than to do that and have to make a game.. So think much smaller?
Just my two cents worth... Also, you guys can hire or approach an indie group of developers, negotiate for them to develop this game with your support, that way if its off your hands they can go wild with it and develop anything they want, and you guys can work on Documentation and support.