There is no doubt Universal has drawn up concept plans of it both ways. And for me, its just too hard to envision what else Universal has that will make its new park competitive with Magic Kingdom. And all indications are they're ready to get park #3 open ASAP. Pouring resources into IOA or USO will not make that happen.
Also, we don't even know of Universal has permission to use Pokemon at this point, but even if they do, I'd expect that in the new park too. All rumors point to making the new park targeted at a younger age, and putting both in there is the way to do it. Universal's existing parks already have that stigma that they're for a little older kids, and it'd be hard to convert that. Especially by removing Kidzone.
I said it before, when the walls came down, and was ridiculed, but I stand by it: there's a real good chance its going to the new park, with Kid Zone being kept as a backup with developed plans just in case things don't move along the right speed or how they want in the lawsuit.