Only cloud hosting providers can provide hosting for themselves as cheaply as google. Microsoft and Amazon (except through prime video and twitch) have shown no interest in entering the fray. The downfall will only come through antitrust.
Federation will be the only real option considering the massive storage and bandwidth requirements. Even then, once an instance starts to grow, they'll have to come up with some type of monetization strategy.
Even a low population instance will likely need many terabytes of storage.
I don't see how federation makes economic sense for video serving/hosting. To do it economicaly you need to have local data centers with peering agreements with local ISPs and good deals for transit. Only big data companies (Google) and huge or specialized self hosts(daily motion, Facebook), can really do it.
Reddit and Vimeo were stupid for hosting video on cloud services for that reason. Reddit wouldn't have been in such an economic crunch if they weren't burning money by serving video on the cloud.
I suspect in the long run it will be doable due to advancements in bandwidth, computing power, disk space and compression efficiency but it's probably more than a decade away.
And even then it might be the case that it's only viable to do 1080p while the big guns can do 8k at 120fps.
They don't. In fact they get demonitised more and more easily for completely bullshit reasons. The majority of youtubers get paid through Patreon and in video sponsorship rather than from youtube itself.