The Exec Order would be of interest as they can't say "no birthright citizenship". Needs to be a bit clearer than that to keep a lot of people from becoming without somemany thusands of them sort of citizenship.
Seriously, what happens when a country wants to deport someone who lacks right of residence (or even the ability to reside) anywhere else? I know there was a cutesy Tom Hanks movie about
one man in that situation, but Trump plans on creating
thousands of such people. Will he bribe some large "shit-hole" country to accept them? Sell them to Saudi or Russia as slaves? Bulldoze them through the Texas Border Wall
™ and wish them luck?