Won't get to try it til tonight (EU)
But still, I remember a blue post (and now I can't find it, typically) saying that at 100 there will be two paths of progression.
Normal dungeons -> LFR
Heroic dungeons -> Normal raids -> Heroic raids [-> Mythic raids]
But why anyone would do normal dungeons at 100 is a mystery to me when getting into heroics is stupidly easy.
Honestly, LFR is easier than normal dungeons. I'm not even joking.