With regards to the subscription only model, I think a lot of YouTube channels would have a very low conversion rate from free viewers to paid viewers. It's one thing for channels that build their viewer base from free viewers and then later have something like Patreon with an optional subscription to fund them, but quite another for them to go paid only.
And how much would people pay? Satellite TV starts at €30/mo here. In light of that, even paying €5/mo or €1/video for one channel would be a poor value proposition for many people.