Given the strides Folty took this season, I'm not sure he can't be that guy - maybe not the "name" everyone wants, but with the confidence of having 2018 in his back pocket I think it's fair to count on him at the top rather than spending lots of prospect capital looking for that guy that can be more than a marginal upgrade over Mike.
When looking for the type of SP you mention, which names qualify? Scherzer's not going anywhere. Neither are Kershaw, Sale, Verlander, Cole, or most of the other "name" guys. When you get beyond them, who's that guy???
He made great start-to-start adjustments against the Dodgers in the playoffs, enough so that I even think he's finally turned that corner - and I've always been one of his biggest "haters". His next step is not being prepared enough for that first start, and I think he's capable of taking that step now.