Firefox

Ideally, it would be a P2P protocol where the main seeder is either the content creator directly, or a service paid by the content creator (who is funded by their audience and/or sponsors).

I believe there are many podcasts that work somewhat like that (minus the P2P part, they just simply use RSS). Some hosting services have features to insert ads into the audio podcast being hosted.. so the content creators still can choose to do that if they want, but the advantage is that there's isn't a monopoly for a single hosting provider and you can access the podcasts from many different podcast apps without needing to rely on a specific website and company that decides how you can watch it.