I'm absolutely certain that Blathers will go back to blathering in the next game.

[Dartpaw]

As part of his character development is trying to improve himself, until Celeste says that his faults make him what he is, and he shouldn't bend backwards to be something he isn't.

This happened before when Blathers went through a bug encyclopedia forcing himself to like bugs, and clearly torturing himself while doing so. And Celeste made him stop, saying the above.

 

[dizzy bone]

I hope so. I miss his blathering... maybe not after every single fish/buy/fossil donation but it would be nice for us to be able to visit special NPCs during their off hours at their home or something (like maybe a section off Main Street where they all live?) where we get to hear more background stories about them! Kinda like how the mole brothers have the reset centre!