The thing to remember is that it's a two-way door: current audiences move on, but we keep making more humans, and they keep "discovering" what youtube recommend

The thing to remember is that it's a two-way door: current audiences move on, but we keep making more humans, and they keep "discovering" what youtube recommends to them, so realistically the threat is "leveling out" rather than "losing viewers" if you run a quality channel that isn't built on slagging others off. Plus, we're already seeing alternatives (or rather, in-parallels) becoming quite established, most notably Floatplane and Nebula as created-by-youtuber(s)-who-wanted-an-off-platform-alternative.