No, resale buyers will never be shut out of changing resorts since in order to do that, the resort has to be removed from the club. And once removed, all owners there would be restricted. I do think that there is a way to make it so resale buyers have a shorter window for changing resorts, and you are only guaranteed a one month advantage. But, as already mentioned, it may have to be something more like a VIP system, then just that.
But, I don't ever see any of this really happening because they are still selling points with what is in place and until that slows down to a point where people are not buying at all, things will remain the same. But JMO!