People who use third party apps are power users, most users simply don't care. I also highly doubt power users will leave, they say that but they're the ones that use Reddit the most, so it's very likely they might take a break for a while but begrudgingly come back in a month or so.
I guess we'll see. Anecdotally, I will stop using it and have been using it since the beginnings. Same sentiment from all long term users. We'll juat see