Have we gotten any hints/discussion on the theme surrounding the land of the new expansion?
As of yet, everything in Harry Potterland has been set within the context of the 4th book. The tri-wizard tournament is taking place, Sirius Black is on the loose having narrowly escaped the Ministry again, Voldemort and the Deatheaters are a nonissue..
12 Grimmauld Place, the Weasleys' Wizard Wheases, the dragon in Gringotts' bank.. are all from the 5th, 6th, and 7th books.. And as we saw in the story, Diagon Alley became quite a dreary place towards that end of the saga..
It's possible they take the stance that the setting is AFTER the final battle(the wizarding world versus the evil that shall not be named, and with the success of the wizarding world the wizarding economy is thriving again.. nice little allusion to Universal Studios itself ). But that then places Hogsmeade and Hogwarts into question. Also certain people being alive still.