One problem would be defining what an "American" is...right now, it's just about anyone. Here where I am, you've lots of so-called "Americans" on paper, yet you can't tell them from foreigners. IMO, they aren't Americans. Deport them along with the rest.
Consequently,"citizenship" means just about nothing anymore...VERY much like the Roman Empirein its later years...and the result will be the same.
-- John D.