I'm sorry I can't, I don't see many stuff besides the squish, garisson, and what model/animations problems of the new models for 5 months?
Of course raid content would require testing but still...
EDIT: I'm well aware that it's IMPOSSIBLE for there to be a release till september of WoD due to Diablo's release there's no marketing miracle saving you from launching near Diablo. They're releasing Diablo in March cuz they know they wouldn't release the expansion that earlier.
Plus the whole new PvP season scheme sounds weird.. Bet you on 5.5 leading to 6.0.