Soundstage 747 will definitely be used again. If they plan on making this the last year for The Walking Dead, then it'd make sense for them to go grand and place it in a soundstage.
It seems like they plan on using Stage 28's former footprint as a maze location to make up for the loss of HoH. Though that particular spot is likely going to be used only once, it supports the theory that HHN will eventually be moved entirely to the Lower Lot and Backlot.