I'm not a Couch hater. I'm not a fan either but I don't think he's absolutely "done". I do think that his career is one of those long term resurrection jobs that you don't see happen very often. Mostly I think that's because of his head. How screwed up do you think he is upstairs and how long do you think he'd have to sit at 3rd before you got that mess straightened out?
That's the problem. In the old days he'd be the kind of reclamaition project that Al Davis might pick up (IF he had a stronger arm so this is kind of hypothetical really) and let sit for a couple of years at the 3 and then the 2. Or he'd go up to Canada (That may very well happen) and get his head back together to earn himself another shot.
He'll get a call from someone, somewhere. QB is so thin around the league that he'll be riding pine for somebody this year. He won't be getting any better doing it though in most of the places that will call.
Fitz makes bad decisions. That's not going to change.