What happens if he loses his belt to Frankie? I'd believe he move up in weight since his coach even said that weight-cutting is very hard for Aldo right now.
It depends how he loses. if he gets totally outclassed for 5 rounds and loses 50-45 or worse, then he might have to fight and win 2 in a row before getting a rematch
Don't sleep on Frankie Edgar. Like everyone else said, a rematch will probably happen or Aldo will move to 155.
Frankie is one of my favorite fighters, but Aldo has incredible takedown defense, is quite diverse and incredibly quick, taking away one of Frankie's best assets. He also works leg kicks like no other -- something Edgar has issues with -- and Frankie has a tendency to run into strikes when he's trying to work his lateral movement to great effect in his offense. Frankie can definitely win, but he gets rocked and Aldo has the ability to finish quick and doesn't let guys recover.
Well once he vacates he will go on to face the current LW champion, most likely Benson. From there he will become the third man to have two titles from different weight classes and the first to get his second title without losing the other by a loss.