>or a wrestling board

It does now, in the form of /asp/ I think :)

However I don't know how well moot's prediction of fizzling out holds for say 8chan, which has started to very much grow in popularity; granted, having roughly some of the same popular boards as 4chan (except for where moderation doesn't matter, like on NSFW boards) but with some interesting and nice top boards, like /leftypol/ which 4chan would never host.

I remember being on 4chan when the total amount of content currently hosted was listed as 50GB. And I thought it would be going down.