I think the feeling at Reddit HQ is that as long as there isn't someplace else for the users to go they will be alright. I mean where else are you going to get a Reddit like experience? Digg? Tumblr? Livejournal? Slashdot? Twitter? Usenet?!? Nothing really compares to Reddit. Personally, I wouldn't feel too confident. I saw how fast Digg and Tumblr collapsed. Even if you don't know the name of the next big thing, it is probably out there already.