>>941658993 (OP)
>Something tells me future administrations won't exactly object to an enormous, resplendent state function space when the present largest indoor WH space seats 79 (shitting me?), and anything larger has required TENTS ON THE FUCKING LAWN.
>For decades.
Meh. Jefferson greeted foreign dignitaries in his bathrobe while laying the foundations of US primacy. Lincoln once made sandwiches for a visiting delegation. FDR had the UK Royals over for hot dogs as they discussed what to do about Hitler. JFK told a dinner of Nobel and other great scientists they were the greatest grouping of intellectual power the White House had ever seen, except when Jefferson dined. Alone.
Something creative would have been to re-do the first floor of the adjoining Treasury Building if he needed a super-big space.
US traditionally understands real power avoids display. Just MHO. I think the real problem is he didn't follow procedures.
The opinion of future Administrations is irrelevant. Congress wields sole authority over DC and federal property. This Congress may let it lie but is in no rush to grant a retro-active exemption, which he will need. When the GOP is out of power Congress will have a ready-made issue to at minimum order demolition at the cost of those involved, and arrest Trump for destruction of Monuments or even Piracy, and usurpation of Congressional authority.
DC juries will convict.