I mean, there have been talks of "what could have been" since at least civ4. I don't think we'll get 2 more expansion packs, and I'm almost positive that we won't get 30 more civs. There's obviously the possibility and even the feeling that we will get more than what we have now, and it isn't just a random, "we wish we could've made another expansion to 5, but now we're making 6," even of that's because this game was purposely released on a big anniversary year. But I'm kind of rambling now. Either way, I think they'll make it to 50 civs and release the next game.