UPDATE: Jets owner Woody Johnson has now announced that Rex Ryan will return as head coach of the New York Jets in 2014.
According to Jason Cole of the National Football Post, the Tampa Bay Buccaneers would be interested in hiring current New York Jets head coach Rex Ryan if he's let go by the Jets, and the Bucs fire Greg Schiano or he otherwise leaves. Those are a lot of 'ifs', making this very speculative, but still worth relaying. For now it looks like Ryan will stay in New York, and Schiano may stay in Tampa as well.
Rex Ryan is likely the best defensive mind in the NFL, having put up consistently dominant defenses in Baltimore and New York. He's flamboyant and a little wild, but his players love playing for him. If the Bucs were to hire him he'd be reunited with Darrelle Revis, and would have some supreme defensive talent to work with in Gerald McCoy, Lavonte David, Mark Barron and Dashon Goldson.
While Ryan has generally run a 3-4 defense, he has adapted to his personnel throughout his tenure and has mostly run a 4-3 defenses this past season. He'd certainly know how to get the most out of each of his defensive players. The question, as with all defensive-minded head coaches, is how he'd run the team's offense. A quality offensive coordinator would be crucial to Ryan's success.
For now, this is all idle speculation. But it would be an intriguing option.