I think you're right that we should be skeptical the ballroom will ever get built. Not only is there the issue of how long Trump lasts in power or even life, but also Trump normally uses building projects as money-making schemes. The longer it get dragged out, the more $$ slips into his pockets.
I don't doubt he actually wants this one--the grandiosity suits him right down to the ground--but they apparently need all kinds of building permits first which could take several years alone. I'm sure he WILL stamp and screech and demand they do it NOW anyway; maybe they will, and maybe they won't.
also the fucking thing is supposed to be bigger than the ENTIRE existing White House. that's not a ballroom, that's a frigging airplane hangar.
be kind of fantastic when this time the workers ICE tries to nab are LITERALLY RIGHT FUCKING THERE