Based on what i'm seeing in the two sets of aerials we've gotten in the past few days, it looks like there's a decent amount of room between Miss Adventure and Crush n Gusher. The plot has potential to be fairly big if disney would move the permimeter of the park into the construction yard just beyond the trees, but Disney very likely wouldn't be willing to approve that.
So that means anything would likely need to be vertical if they were to build there. A drop slide like Ihu's or Oh Yah/Oh No comes to mind.
Of course i'm just speaking in hypotheticals. Besides, there are plenty of other expansion pads in TL and Shark Reef sitting abandoned: