Yeah, I was wondering if they might level the "studio bungalows" (what are they even used for now since no filming occurs in the park?) which are on the other side of Jack Sparrow/TSMM. If you make the walkway between TSMM and Jack Sparrow into a new pathway, it could lead right into TSPL. This would put it essentially right next to TSMM and would allow the area where the Backlot Tour entrance was (and the special effects tank and such) to be used for other Pixar properties.
I'm envisioning in that scenario that once costuming gets moved, you can have a new subland and pathway on the other side of the TSMM (and Soundstage 1) building.
It would be interesting to know at least where new stuff is going -- like how much, if any, of backstage areas or the old tour will be converted to guest accessible space.