I think what will eventually kill it is the fact that it is a near $50K specialty truck that has the DNA of a desert runner. To date there is not a crew cab version. If the fuel economy for the 6.2, that has yet to be seen in the wild, is anywhere near as bad as has been stated then I think it will be a hard sell when oil goes over $100/barrel again and gas at the pumps hits $4/gallon. I know a lot of people say they didn't buy it for the MPG but $100 to fill up your truck will get old fast when you are only getting say 12 MPG, leaving your pockets draining at $0.30 a mile. The Raptor still lacks the towing capacities of a full-sized pickup rolling in a 6,000lbs (which ironically is the same towing capability as the Tacoma I had).
A year or so after the newness and exclusivity wears off people will start to nit-pick more and more about the Raptor's shortcomings leaving more on the lots. Remember there are a whole lot of people who want it, or own it, that have no intention of using it as an offroading monster.
I am not bashing the Raptor, why would I? These are just the thoughts that came into my head concerning the collapse of the Raptor dynasty.