I think if Winnie doesn't build on this platform, someone else will. The Ducato and the Transit vans are going to be here to stay (as fleet sales are a critical part of domestic auto makers' bottom line), so these platforms will not disappear like the VW vans did.
What I'm curious about is what the European motorhome makers will do. There are three major differences between their designs and the ones here (black tank instead of cassette toilet, generator, and A/C unit), but those are relatively small, and they have years, if not decades of experience with building on the Ducato chassis. Hymer could eke out a cult market fairly easily with a short "C" with a decent floorplan and an aisle shower.