They already said on MoP beta and I believe even at blizzcon that LFR will "replace heroics" - so there is no need to make 5man every tier to bridge gap between last tier and new tier for "those that fell behind gear progression" or anything like that.
Old system:
Normal 5-man -> heroic 5-man -> normal raid -> Heroic raid (after wotlk-Naxx)
New system:
Leveling 5-man (called normal) + Scenarios -> Normal 5-man (called heroic) -> LFR ("new heroics") -> Normal raids -> Heroic raids
Thats how it is, and thats how it will be for rest of expansion and maybe even next one unless they go "we learned that players wanted 5-mans so we make 5-mans relevant again!!"
They probably should rename the difficulties on next expansion.