The Gen 1's may continue to decline in value for a little while, but then I think they may see an uptick. They're the first of what may turn out to be an iconic vehicle, maybe like the corvettes or mustangs. Early model year cars of those marks go for high dollar. The Raptor has the same chance, but ford needs to keep the ball rolling for a while.....
As to the value of the current model years, well...ford is cranking them out by the hundreds of thousands, so that will drive down values. I bought mine used, before the 17's came out. At the time, there were like 6 Raptors for sale in Washington state. I was told straight up that there would be no negotiation on price at all. I paid $52K for a 4 year old truck with 24K miles on it. It was (and still is), one of the top three best days of my life. The salesman is a long-time family friend too, still is. He wasn't bullshitting me.