I would guess that we're probably still too close to tell. For instance, younger siblings will have easy access to their older siblings' book copies, to which the initial owners are still too attached to banish to the attic/basement/giveaway bin. The movies are still being rerun on cable; I'm not sure if the last one has even reached [basic] cable yet.
I was reading William Goldman's Adventures in the Screen Trade (published 1983) last night and he had some interesting comments on Star Wars (ep IV). The section was about movie endurance over time, and he specifically mentioned that he and some friends watched Star Wars again (~5 years after initial release) and felt "embarrassed" by the special effects, the acting, etc. (I tried to find the exact passage online to paste here; no luck. Maybe when I go home tonight I'll type it out.) They probably would not have believed, in 1980-whatever, that it would still have such a following in 2013, be rerun frequently on cable, be in the top 20 of AFI's "100 years, 100 movies" list... It's safe to say that most popular stuff inevitably goes through a passé phase and who knows whether or not any one franchise/trend will be the one-in-a-hundred to come out the other side.
Edited because I got my roman numerals backwards. :\