Apple computers in general are not going to enjoy the same resale value they have in the past. It's a different company with a different philosophy now that pushes much more into planned obsolescence and that has to kill the resale value.
My 2004 powerbook lasted me into 2009 before it fell far enough behind that it became limited. It was certainly slow, but it could still do pretty much anything a newer one could do. Now my early 2011 MBP I just bought last August is apparently the oldest apple laptop model that will support airplay. Since the model came out in Feb, it will be 17 months old and already hit the limit. Mine will be 11 months old and I didn't think buying a 6 month old mac was a problem at the time, but now I regret it, not because of the laptop's inherent limitations, but because of apple's new game.
Not everyone will care about airplay, but it will soften the demand and therefore lower the resale price of anything older. That is way too soon to start killing off a product. It sure seems like Apple is trying to build in a 2-year expiry date, and that has to destroy resale value. Someone may be okay with not having the latest and most powerful, but when they're also locked out of new features just because...why would they buy the used gear?
What will happen to the rMBP when it's 3-4 years old and needs a new battery? People here talk about selling it and moving on to a new computer, but that only works because somebody is willing to buy the old one, and if that's going to need a $200 replacement *and* have features locked out from os 10.10 or 11, it's got to kill the resale value. With the rMBP, the days of $30 ebay batteries that take 5 minutes to install are over.