You know, I agree with you, but I fear the damage has already been done. Fifty percent of the next generation of Mexico and Central America are already American Citizens. Thinking we can get a law passed by gutless Congress is a stretch, but making that law retroactive would be a miracle.
You are seeing reality...sad to say.
US Constitution, Article 1, Section 8:
No Bill of Attainder or ex post facto Law shall be passed.
Can't do it retroactive.