Paul Ranger is a unique case. He is unquestionably an NHL caliber defenseman, but the year in the AHL was meant to be a refresher course to get him back into NHL shape, and as a stepping stone to an NHL contract should he decide he wants to atually return to the game.
There's nothing tying him to the Leafs for next season. He'll likely be one of the most sought after free agents. I think the Leafs have a very good chance of landing him, given that he seems very happy to be playing for the Marlies and playing in Toronto.
I think the Tampa Bay Lightning have a very good shot at him too, though, so I would consider them as contenders for his rights as well.
Personally, more than with any other free agent in years past, I hope he goes wherever it makes him happy to be. Rather see a guy like him, who embodies the purity and spirit of gamesmanship and love of the game of hockey, to be happy and in a place he loves than to simply have him on my team if it wasn't the right place for him.