Why not both?
I belong to a few Raptor Facebook groups and forums and I can say without a doubt that many Raptor owners will be trading their trucks in on the Hellcat TRX. From what I see, about half, if not more, of the Raptor owners in these groups are not "Ford" guys. They are the type of people that rush out to by the latest & greatest. For many of them, their Raptor is their first and only Ford. If Ford wants to retain these types of customers, they need to make the GT500 powertrain (or maybe even the 7.3) available in the next Raptor.