I donate to a few creators. As for YouTube, Google can close it down for all I care, we'll figure it out. We'd probably better off, in fact.
EDIT: interesting thought experiment. Adblock is so universally adopted through aggressive marketing that ad supported internet as we know it is forced to adapt...where does it go?
That all said - geocities existed back in the day without getting much out of the proposition except some minor side-loaded ad revenue and network value. So I don't think a content host would ever be in a position where they find no benefit in hosting and, again, hosting is so incredibly cheap to do at scale that only a very marginal value is required to get into the black.
1. So a word-press site is going to have a lot of wp-* styles all over the place - but wordpress doesn't force a giant WP logo in the top-left of everyone's site.