There was more than one unconstitutional angle to HERA. "No court may take any action" transferring all rights, powers etc "to the agency" nationalization or exaction, uniform bankruptcy laws, right to a fair and speedy trial etc, ... Plaintiffs only focused on separation of powers in which the remedy was weak in the first place. Initial conservatorship also was not challenged there was a lot of material there too, why didn't plaintiffs sue the board?
That may be a blessing in disguise. If there is a party split in the legislature and after an election the executive wants funds they can devise a scheme to sell their stake to the public, right now potus gets whatever funding he wants because of the current power structure. But I wouldn't rule out a plan under biden and the current power structure either.