Twitch deciding to change how much money they take from there users might actually fuck them over. If its one thing that gets people concerned enough that they might consider going to another site despite the differences between the two, its when you decide to mess with their income; because for all of the Twitch streamers that complain about how sub-par Youtube's streaming tools are, it has at least stayed consistent in how much it takes. I think they'll be willing to deal with the negatives if it means they can still pay there bills, regardless of what they've said previously.
Of course we'll have to see if this is just a fluke or if Twitch decides to double down on it. If we see a bunch to Twitch vtubers start to add in Youtube streams in the schedules more often, some kind massive switch could be very plausible.