There are lots of laws already on the books that the executive could enforce to put a stop to illegal immigration. Trump was ignorant of many of them, and none of his GOP handlers were going to tell him, so he tried his best with the wall and ending DACA.

Sadly, you are right, any other GOP president will not have the spine Trump did to try, and those that do will never be elected. Most likely no GOP will be elected again until GOP looks like the Tories or worse.