I always wanted to know what became of Harvey Keitel's character (Charlie) after MEAN STREETS. Not that I'd ever want to see a sequel, especially now, 35 years after the original. Still, I always found something about that character worth saving, something redeemable.
Yes, that'd be fascinating.
SPOILER:I inferred from the ending montage that his uncle approved (or didn't disapprove) of Michael's hit attempt. If so, Charlie's career as a budding gangster would have been over. A guess: he left NYC and entered the priesthood.