They are moving the Mill and Tech Building to the studio Tour, WOTW sets are rumored to be moved and or just gone later this year for more studios space and Park lake (where Creature was filmed) is rumored to become sound stages.
From what it sounds like to me, is the lower lot is where most of the next new attractions will go besides the simpsons redo.
In some universal where Universal had more money, I could see them moving more things off site if they had the WB lot down the streets but since that door is closed. My guess is the Lower lot will add more things over the years and the Tram area will not be used for more theme park stuff outside attractions for the Tram