Does it matter where they'll go? People will always find some spot on the internet to have conversations after a given platform hits the friction threshold, and some might not even go anywhere: They might just leave.

Where people will go doesn't really matter, because there are a billion places they can, and there's not always a clear migration path. Sometimes, a social platform just dies, and its communities form a diaspora on different platforms, without any "clear" successor (like what happened to Orkut), or just stop doing the whole social media thing (many Google+ contributors no longer post online anywhere).

My question was kinda selfish. I want to move now. If there are a billion places, please tell me so I can move there now before the masses arrive and even that gets ruined :)

There's no easy answer to this. A billion different places users could go doesn't mean they have active communities, and if I mentioned where I like to hang out on the internet, those areas would probably get ruined.

Instead, I'll mention two platforms some of my friends like, to avoid taking the cost of a ruined platform myself:

sqwok.im: This one is the most microblog-like of the two, but it's also the least conventional. The quality varies; the front page only looks good every once in a while.

tildes.net: This one is invite-only, which helps mitigate the masses jumping in somewhat, and is run by a former reddit administrator. The existing community isn't great, but it's good. Friendly enough people.