So taken from the complaints about 4.3 and Cata in general, I propose this question:
Blizz is making a new tier, and is thinking of one of these two types of raids:
Option type 1: The raid has 100% new environment, something never before seen in WoW, but all the boss models/skeletons are pre-existing models. The final boss is also a boss that has been defeated in a raid in some point of WoW's history (but is in a totally new atmosphere)
Option type 2: The raid is 100% reused and rehashed environment, but all the boss models/skeletons are brand spanking new. The final boss also has a unique model/skeleton and is new to the lore