I think he should test the MotoGP waters.
But if he goes totally MotoGP next year, it would be a good thing for Spies, but a bad thing for AMA. No one else has a chance to beet Mladin... Disalvo isn't making the run at it I thought he would. If Mladin does retire, then it'll be competitive again.
I hate to disagree with Ben, but I don't think AMA's top 6 riders would match up with the top six riders in ANY series, at least not MotoGP.