Serious in sense that it's a place to make money? Probably Zero. If you count Live-Streaming, then 1 or 2 more. If we talk about alternatives to host videos? Probably dozens or more. If we talk about places for "high business" (proper company, not some lone creator in his ikea-flatroom) to make money, even more, but most of them are also specialized. Social Services like Instagram, Twitter, TikTok and even reddit are somewhat of a competition for short clips (<2 min), but making money there is a bit strange I guess.

Youtube at the moment is the single place (for videos) where you get everything, from the high number of potential customers, to proper and easy tooling for managing stuff coupled with a good level of potential income. And as long as Youtube is to big to fail, this will not change.

Nginx can still serve videos with a plugin. There's plenty of ways to self host it.

The problem? You don't have YouTube to cover your hosting costs.

I've seen Nebula been promoted by some content makers on Youtube. Otherwise alternatives like PeerTube.

A lot of creators are trying to advert nebula as a way to watch their videos, but I haven't tried it.

I've seen people moving or at least having a duplicate channel on Bitchute, DailyMotion, Rumble etc.

They’ll have to pitch their ideas to Netflix/ATT/Disney/Comcast/Apple/etc. Or setup their own website and make deals with advertisers.

There's Twitch and then I see a lot of people doing talk shows on Instagram. Definitely more than there used to be.

Vimeo?