I don't care about birthright citizenship either way, but I care a lot about the rule of law. Trump doesn't care about the rule of law and values his own whims over the constitution. So the real test here will be whether America still has rule of law, whether the constitution will be followed. The 14th amendment says:
"All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside."
If Trump wants to remove birthright citizenship, then he should propose a constitutional amendment.