There's talk of a 3rd movie and spinoff.

and there's also already some sonic 2 movie happy meals appearing at mcdonald's, even sonic's creator, yuji naka wants in on that

A friend of mine told me after the 3rd movie, Jim Carrey will be retiring.

@Mr Magic

shortly after that announcement jim made a post mentioning his curiosity to play "fat robotnik", so i don't find what he said to be very believable

Carrey has been bouncing back and forth with retirement for awhile now. Given this series has been his only big hit in the past 15 years, I don't think it is out of the realm of possibility that he eventually decides to hang it up after the third film.