I see both sides of the argument. Destroyers are great drivers and would (theoretically) sell well no matter how hard Innova pushed them or whose signature was on the disc. However, DG'ers are an often fickle group. They seem to want to buy discs based on marketing hype and certain pros throwing them. Plus, many star Destroyers seem to be bought for collector reasons, hence all the sniping about the new stamp.
What I think is interesting is the recent (and rampant) hype around Discraft. Suddenly Forces and Buzzzes are super hot commodities. Paul really is a big name in DG. Wherever he goes, success in disc marketing/sales will follow.
What will be interesting to see in the future is how many people threw Destroyers simply because Paul McBeth did, vs. how many people throw them because they really like the mold and get good use out of it.
I'm no expert on market trends, but I'd assume that star Destroyer sales will remain fairly steady in the future. The mold is well established and thrown by many, many good players. I can't see tons of guys abandoning the Destroyer simply because Paul switched brands. That said, there will be an immediate uptick in interest in Discraft molds. Especially the new molds they've just come out with per Mcbeth's desires.
I agree with all that you said. The destroyer was huge before it had Paul's name on it, and will stay huge now. It's one of the best discs to come out in the last 15 years. When you combine Paul's name with a legendary disc, it will definitely sell. The buzzz fits that same category, in my opinion. People argued buzzz vs roc for years before Paul's name was on the roc(3), and now his name is on the other end of that argument. We'll see how that goes. Even though I think he might end up with the wasp in the end. With Paul now throwing the force(which for all intense and porpoises is a destroyer copy) it will definitely gain popularity, but I don't think it will unseat the destroyer. We'll see.