I think we'll keep it open for people to play whoever. Once I'm done with 'the story so far', I'll detail the kinds of factions/rolls people can play, but thinking about it, I might not limit it to anyone. I'd be more than willing to allow someone to RP the American President, for example, if they could prove they knew their stuff about the American political system etc. 

I don't know, it's a young idea that I'll keep chipping away at. If you're interested, subscribe to this thread. I'll more than likely be fleshing it out on a daily basis, and any input or suggestions/criticisms are always welcome.