IF Flynn was cut, I wouldn't mind seeing him on the roster. That said, some team is going to be stupid enough to trade for him... just like the chiefs did with Cassel.
The problem with Flynn is that I doubt he is content with being a backup... and if he once again does not get a starting job, how much drama/split is that going to cause in the locker room chemistry? I think Jason Campbell knows by now, that he has had his chance, and being a backup/mentor to a young guy is his role.
I think Campbell would be a better mentor to Geno Smith than a feisty and competitive Flynn.
Then again, competition can be good.
It's a double edge sword.