This is unlikely, because youtube has one thing that no other platform does, creators. How many youtubers would actually be willing to post on another website, let alone exclusively? How many fans would actually follow them? For already risk averse youtubers this is unlikely.
Many, actually. There are quite a few active alternatives now, such as Nebula for science YouTubers and Odyssey. Last I heard Linus Sebastian was working on an alternative as well.
It seems that most content creators are quite worried about the way YouTube handles (de-)monitization and copyright strikes. Many CCs are also streamers and use YT only as a side channel. Sure, YT still has a large footprint, but it's not as solid as it used to be.
There are, but generally for specific interests, and not nearly enough to challenge youtube's market domination. Without something dramatic youtube effectively has monopoly control of supply and demand.
