And just to confirm the area known as the Mound is at the top left of this aerial shot - it's the land opposite the BB house:
This isn't a new plan either - it's been knocking about since 2006 to clean out that land and build new studios on it, with plans back then specific in stating the BB house would be retained. There is no reason it won't be now - but if Elstree decided it was in their way you couldn't blame them as they need to plan for future decades while BB's future is probably only a matter of years.