I foresee this being very successful if they make the barrier to entry for the viewer essentially zero. People have been starved for a YouTube alternative for the better part of a decade now.
The bonus for users will be (hopefully) fewer in-video sponsorship ads (I know all about squarespace and nord vpn, thanks), and no algorithms sending you content you don't want. Less discoverable of new content, though. I suppose "click like and subscribe" will turn into "become a patron!", so that's a wash. Hopefully there won't be as much self-censorship, too, because they have another revenue stream if a video gets demonetized. Or maybe they will put the controversial ones on Patreon only.
I'll be interested to see how this turns out. If it becomes competitive, I suspect YouTube will ban Patreon links instead of doing the more sane thing of partnering with them.