While I see where you are coming from with regards to niche audiences, I genuinely don’t believe that most of the streaming audience is going to put much thought into which service has the most stuff they like. Netflix is a monolith that has probably 100 (?) good movies on it, and 2000 terrible movies; it has 20 (?) good shows on it, and 1000 mediocre ones. For most, it’s a matter of finding something that’s alright, not necessarily finding a repository of all that good shit they love.
A great recent example of this paradigm is Bird Box. This movie, which is, by nearly all accounts, completely average at best, absolutely EXPLODED (in part due to Netflix’s clever literal inception of social interest in it - a different subject for sure) partly because hundreds of thousands of people were in a house, off work, bored, and maybe depressed over the holidays, with nothing else to do besides flip on Netflix and see what’s on. Netflix showed them a new Sandra Bullock movie and told them it is good (98% match!). I think this is enough for most Netflix users: show me something to say “yes” to.
Anecdotally, I have had dozens of experiences trying to help people access the movies or shows they say they really want to watch on unconventional (to them) platforms, and nine times out of ten that person has decided, “eh fuck it, not worth it.” It’s frustrating to witness, just as it’s frustrating to watch as people shake their invisible chains at Netflix when it removes movies and shows from its service every month. Those things are usually available elsewhere, be it rental or another platform, but Netflix is what they’re accustomed to, so…
I do think niche services will continue to evolve, and hopefully flourish, and for that, I’m grateful, but I don’t expect a sea change due to content availability or quality. It really seems like convenience takes precedent over content appeal for most, so whichever service is most ubiquitous, easiest to use, and cheapest will probably be the one that rises to the top.