Usenet's just an example. Its hosting at another site with better search tools could (I assume) be dealt with relatively easily given that it's pretty much just text. There may, of course, be issues of which I'm not aware. After all, this hasn't happened.

By no means though is the ongoing archiving and sharing of petabytes of complex web sites and other information repositories a simple problem even if the data were readily available and the issues associated with rehosting copyrighted material worked through.