Lorenzo and Marquez would pretty much both have to be incapacitated so that Rossi could battle it out with Pedrosa for the championship. (With perhaps a few challenges here and there from Crazy Joe)
As much as I like Rossi, that is the current reality.
I'll give you MM winning again this year, but Rossi keeps getting closer. He's no longer the impudent wild child with preternatural talent that overcomes all obstacles. He's now the wily greybeard who has his blood up because he sees a target that's attainable. What made Valentino great in his youth, that ultra-competitive spirit, still lives in his heart. He'll sign for 2 more years and Yamaha will bend over backwards to build a bike for him. Who can guess how much cache, and cash, the good Doctor brings with him to the piano factory.
As for George L.? His physical condition keeps improving