It's highly unlikely. Usually when managers part way there both sides aren't seeing eye to eye and there are some hard feelings. I'm sure there were differences of opinions. However, Jon couldn't really have left on better terms all things considered. He's really one of the most likable guys in the game.
Gibby was the best of old school and new school. He rarely bunted...used non traditional lead off guys. He'd get into an altercation with Josh Donaldson. No one was immune to being called out and yet 2 days later they'd be best of buddies. Guys loved playing for Gibby.
If the Jays ever got rid of Montoya, Shapiro is smart enough to give Gibby a sobering thought. He did a lot of things right. Under the right circumstances, if there were no better options, there is a shot he could come back. It's highly unlikely, but you never know.