Pornhub could start Videohub tomorrow and shake things up if they really wanted to.
Otherwise there’s Odysee (bad name, linked to crypto but good interface) and Peertube (federated but searches aren’t* so it will never catch on), but people aren’t too fond of those.
* I know about Sepia Search. People shouldn’t have to use yet another website to find the videos they want on Peertube. It’s stupid.
Pornhub could do that, but there’s a reason they haven’t. Video delivery is insanely complex and expensive and consumer tolerance for advertising on those platforms is low. With no other way to sustain and income from it the only option will be loads of smaller sites or a paid site.