>>53645765It feels a little more steady-state than that. The leap from static video content to livestreaming was much larger than what amounts to a genre difference between Niji and Holo.
The situation is starting to mature and fans are finding what they like and sticking to it. You'll have new comers appear that appeal in areas Niji and Holo aren't touching, but in some ways that's already Twitch; gaming vtubers who are actually serious and competitive stream there (almost entirely FPS).
The English side is just a completely different culture. English fans either subscribe to the idol model, the men of Nijisanji, or the Twitch model. I guess the one area that's somewhat untapped is political commentary, like the Hasan Piker of vtubers, but I don't know how much appetite weebs, even ironic ones, have for that sort of thing.