The Meaning of “Natural Born”: What if Blackstone Was Wrong?

In thinking about the phrase “natural born Citizen” in the Constitution’s eligibility clause, I have assumed (1) that it follows from the English law phrase “natural born subject” and (2) that “natural born subject” at minimum meant anyone born within sovereign territory (apart from children of invaders and diplomats).  The latter point seems clear from Blackstone, who says as much, quite clearly.