It would be really tough. I do think YouTube provides a lot of value by making its videos accessible to everyone.

Plenty of closed ecosystem streaming services exist and they continue to be niche things where creators who had no audience before YouTube are trying to keep going. I'm not sure how long the likes of Nebula and Floatplane are going to last honestly, because they have fundamental discovery issues in both directions:

The creators need a constant influx of new viewers to replace people growing out of their content, and the viewers need a platform where they can experiment with new content without a big paywall upfront.