The fast pass/reservation machines are already up for Diagon Alley. Universal learned from Potter 1.0, with Diagon Alley being fairly tiny and park being PACKED, it would be criminally cruel for people to line up 3 plus hours during the Florida summer months.
From what I've heard, Gringotts and Hogwarts Express will not have Express or any Fast Pass (along with Forbidden Journey). HE forcing people to buy 2-park tickets won't be a deterrent, I heard from Touring Plans that most of the hotel rooms at Universal were booked this summer which they said should indicate huge crowds.