Next thing you know Mexico will be demanding Texas back....
O’ Wait.....
Well, they can have Austin....
The Mexicans had their chance. Alfred Zimmermann offered them Texas, New Mexico, and Arizona if they would side with Germany in WWI. They didn’t take him up on the offer. (Of course it would have required Germany to defeat the US for the promise to be carried out...and we didn’t have a Jimmy Carter or Barack Obama as President of the US at that time.)
Basically everything south of Austin is theirs already.