Supreme Court rulings since adoption of the citizenship clause of the 14th Amendment in 1868 have had the effect of creating four exceptions to “all persons born...and subject to the jurisdiction thereof...”
1) Reservation and tribally enrolled American Indians prior to 1924.
2) Persons with diplomatic immunity.
3) Members of a foreign invading military on U.S. soil.
4) Persons on foreign public ships within U.S. territorial waters.
A person’s legal status can change by congressional action (for example the 1986 Immigration Reform and Border Control Act of 1986 which gave legal status to 2.7 million formerly illegals) so I agree with you that Congress could pass a bill and a president could sign a bill into law that withholds birthright citizenship from the children of illegal aliens.
Whether such a law would be upheld as constitutional is anybody’s guess and would depend on the ideological composition of the Court at that time.
Good, we agree then.
Here’s my take on what will happen if Congress passes the bill you described and gets challenged ( as it surely will ) and it reaches the Supreme Court ( assuming we still have the present members ):
IT WILL NOT BE UPHELD. The following are SURE to go against it:
Kagan
Sotomayor
Breyer
Ginsburg
Kennedy
AS for Roberts, it will depend on which side of the bed he wakes up.