As I mentioned previously, the Enclave Clause (Art 1 Sec 8 of the Constitution) specifically limits federal land ownership/control "over all places purchased by consent of the [State} legislature...for the erection of forts, magazines, arsenals, dock-yards and other needful buildings." THAT'S IT! No other purposes! Thus, if the feds want to expand that list to other objects, then the Constitution needs to be amended. Neither Congress nor the President is empowered to issue edicts or to pass laws in this regard which do not comport with the Constitution, the supreme law of the land.
So, while I'm pleased Trump and Zinke are trying to administratively reduce Obama's and his predecessors' obscenely greedy land grabs within various State territories, my advice to the Administration is to consult the Constitution and fulfill your Constitutional obligations. Respect and uphold Art I Sec 8 of the Constitution.
Let there be no mistake, folks. The blame for this federal imperialism falls squarely on the feckless, spineless States themselves. Their lack of principle, their ignorance of their constitutional authority in such matters, and their greedy acceptance of massive federal handouts over the years (bribes) have enslaved them and their citizens. And now they whine and look to their enslavers, the feds, to bail them out of a situation they themselves created by permitting this lawless federal land grab in the first place. Jerks!