Only time will tell. You make a logical comment that the performance of the new Scat pack at a cheaper price will impact used values of SRT's from few years ago. I agree it will have an impact but not too much. Used car value guides aren't a good predictor now because these cars are just coming out and in the new generation challenger history there hasn't been an R/T with an SRT engine. For many folks thats all they want and could care less about the brakes and suspension. Those folks turning to the new R/T will impact demand which will impact used prices. But that's going to take sometime to run its course. I wouldn't drop my '11,'12,'13,'14 SRT because of the potential impact. I would however drop my '08,'09, and '10 with the smaller 6.1 because I thinks thats really where the hits will come. Now you'll have factory stock R/T's kicking the crap out of SRT's which really wasn't the vision.
Though, I also agree the new SRT will be an odd duck. Most guys (myself included) wanted the baddest Challenger I could get which is why I got an SRT. Now those guys are going to go Hellcat and the retro group that can't afford a Hellcat are going to go 392 with a Shaker. Personally, that would be my choice if it is wasn't for the Hellcat. SRT or not, that new R/T 392 with Shaker and middle stripe in B5 or Sublime is just awesome. You see the picture in the brochure...just sweet.
I see the non-hellcat SRT as future disapointment for the owner. Looks like a Hellcat from the outside but I suspect everyone will ask..."oh is that a Hellcat"...to which the answer will be NO. :-( I bet that gets old after awhile.
the non-heellcat SRT is probably going to be the rarest of all the models. Of course that's just my opinion