Given the Constitution, Could 2 Million more Immigrants come?

  (Note added 4/4/18: I did not think to look up before I wrote this whether children of Americans born abroad are U.S. citizens. They are. This invalidates the meaning of this blog.)

   If being a "natural born citizen" applies not only to those born on American soil, but also to those born abroad to American parents . . .

  If we recognized this might be what the U.S. Constitution suggests . . .
  Then, would a number of Mexicans -- happily fitting the description -- cash in and rush across the border into the United States?
   Estimates on how many U.S. citizens live abroad vary from 2.2 to 6.8 million. If it is hard to come up with that estimate, it seems it would be even harder to come up with an estimate on how many of them have given birth while living abroad. But, let's say that, on average, each foreign-living American has given birth to just one child.
   That's 2.2 to 6.8 million people suddenly qualifying to move to America. That's 2.2 to 6.8 million people suddenly discovering they have full citizenship rights and there is nothing to prevent them from coming here. The biggest chunks would be coming from Canada and Mexico, but they would come from other countries, as well.
   Those opposed to expanding immigration would be vexed, but should they be?  Should they be upset? If the Constitution allows it, why not just support the Constitution and let them come?