This is a waiting game. London Vatican and DC are connected. All the recent shenanigans at the Vatican are all related to DC. Trump's visit to the Queen and Pope when he was in office were putting them on notice.
My friend pulled all the bankruptcy records.
It was never the Winter White House. The Marjorie Post wanted it to be and tried to make it happen for decades, but officially it never was. https://www.smithsonianmag.com/history/history-mar-a-lago-180965214/
Trump could change that, but the location of the legal White House is a matter of law. See "The Residence Act of 1790"; https://guides.loc.gov/residence-act
Like others have said, it would seem to be a bad strategic position and difficult to secure on the edge of the water.
I know it's never been official. It was called that. But as someone pointed out in another thread it has a SCIF and is capable of running operations.