My main WTF is why did Hobbit lose that many people since ROTK. No combination of external factors can have such a huge effect. It simply must be that they don't consider this as a movie in the same series and didn't give a shit.
I don't believe one iota that 3D is the culprit. Just last year DH2 made over $100m million. Maybe it hurts a bit but you don't lose 80% of your audience because of it.
#4 is still very much possible. The odds were always in favor of TDKR to win and after the performance of TA, #1 was out of the question anyway. Nobody had THG that high on their list, though. So really, Hobbit might be just one place lower than many anticipated after July.