As the sibling comment states, Twitch is an alternative, but I think that however big the gaming and live video market is, it doesn't generalize to most YouTube content. I'm not sure if Vimeo has ever reached the same level, every time someone on HN mentions them, a creator has said they tried and got no traction/views on Vimeo.
Patreon is odd, they host some exclusive content, but it seems nearly all creators retain their YouTube channel for discovery and Patreon is mostly for processing the donations. I guess in a way, they have siphoned off some YouTube functionality, taking the cream off the top (paying subscribers), and letting YouTube do the expensive part of hosting the content.
I suppose that short of the feds swinging the anti-trust hammer and breaking YouTube into 3 equal companies that compete in the same market, the YouTube monolith is here to stay by market forces alone.