aren't you sorta talking besides the point? I don't see how immigration less or more reduces government debt meaningfully. I understand paying for social security (SS) is a decent fraction of the debt load for the US but solving SS does not plug the holes.
if I'm generous with your proposal; wouldn't you still find immigrants applying for citizenship and eventually pulling from SS? most immigrants are younger and we should both be able to agree, they'd likely want to stay if they could.
I feel like your biases are coming through with a lot of this, the answer to our debt problems will not factor heavily with immigration.