The thing with the resource sharing is that it's peanuts compared to what youtubers earn off of other sources of income; sponsorship and product placement deals (which I'm sure is a thorn in Youtube's eye, unless they get a slice of that cake), Patreon is a really big one, and merchandise sales. I'm sure that Youtube ad revenue is in 4th place with regards to income for youtubes, especially since the 'adpocalypse' wherein advertisers pulled out of youtube and stronghanded them into a strict demonetization practice.
Anyway that said, there's enough competition for youtube to ensure that these channels don't have to die; it's just discoverability that is the issue. Youtube does not have exclusive rights to any video uploaded (although I'm sure they have negotiated exclusivity contracts with some), so anyone is free to mirror their uploads elsewhere, just in case. I'm sure there's software out there that makes cross-posting videos easy.