So..I was just on twitter, and I went to GC's page and found..this..
Player: "Wotlk gave us the random dungeon finder, cata gave us LFR. Which new mop feature do you think has had/will have a huge impact?"
Ghostcrawler: "We haven't announced it yet. "
....What the hell could it be? 0.o
Despite people's gripes with either or, LFG and LFR have really helped the game in one way or another. It doesn't depend on your personal opinion for one or the other, but it'd be hard to admit neither of has helped the game at all.
What could it be?
Only thing I have to guess is new Player Models, but that's really all.