I don't really think he has a choice in the issue. He made it too clear from his 24/7 that he fights people at their best and where they are comfortable. There is literally no one at 147 from a skill, and more importantly from a business standpoint that make sense. Canelo IMO is literally the only option. Plan B would be a May/Cotto 2, which makes sense from a business sense, and also to hurt Canelo's feelings for thinking he can call the shots and taking his plan B opponent away from him.
^ going that route would rustle a lot of jimmies though, especially the fans.