My big three (right now) are CFB (college football), Golf, and Warhammer 40k. I think warhammer 40k and golf could easily transition as they arent as confederated. However CFB is a pretty tight community with its own ranking polls and a ton of stuff built by the moderators and communities. That said I'm pretty sure a lot of those polls utilize reddit APIs for user verification. And that could be a real problem if Reddit messes with the APIs too much.