To nowhere. It may take some time getting used to not watching my favorite content creators, but I think I'll manage just fine. I'd rather not use youtube-ish sites at all instead of being forced to watch ads every few minutes.
A lot are also on alternative platforms like nebula. It's true that it's only a select few, but they tend to be also the most interesting YouTube channels.
Well, people will get more and more upset about YouTube, and we already see a lot of new Twitter Alternatives, for example.
I could imagine the same development for YouTube.