It was decided long ago, when our Constitution was ratified.
The question now, is whether Constitutional originalists or transnational citizens of the world win out, as far as enforcement of the Constitution, or relegating it to the ash heap of history.
Barack Hussein Obama serving a full term of office unchallenged will create precedent. The Presidency of our nation will be opened to the world. We will no longer be self-governing, and will no longer be in control of our own destinies, or able to affect change in our own self interest. We'll be beholden to ... what?
Who knows.
So far as I know, the Constitution does not define terms.
The courts have given definition and meaning to many of the clauses of the Constitution. So far as I know they have not directly tackled the meaning of natural born citizen.
Absent some writing from the Framers as to the meaning of Natural Born in the Constitution, I would assume we then look to English Common Law at the time. It is my understanding that anyone born in the empire was a British citizen, unless they were born to a foreign diplomat.