That's all well and fine, except the it was CONGRESS and people in the affected states that fought Senator Cruz, and every previous try at doing what Trump has just proposed today. Those same adversaries will be there for Trump.
There is a difference between one Senator trying to get 65 other Senators to agree with you and being the President who directly controls the Treasury and Department of Interior. The big lesson from Obama’s presidency is that direct Executive power over the agencies allows dictatorial action that takes the Court system years to address.
The Federal government sells off property every day at IRS and Marshall auctions — property originally seized from citizens but is the property of the Feds when auctioned off.
Once the Federal land is sold into private hands, it will be pretty tough to take it back. An Eminent Domain fight would have to prove there was an overriding public use. With a separate court fight for each parcel I don’t see that happening.