Short answer: yes, when he reaches the minimum age.
Slightly longer answer: yes, when he reaches the minimum age because his mother is a US citizen and conferred citizenship upon him at birth.
Even longer answer than that: yes, when he reaches the minimum age because his mother is a US citizen and conferred citizenship upon him at birth. He is eligible for a US passport as a citizen at birth, ergo, he is naturally born a citizen and that is the only standard that anyone can point to as having some sort of proven track record behind it. McCain, Cruz, Harris, Obama, Rubio all met this standard and not a single one of them was disqualified by any court or legislation from serving in the office of the Presidency. Folks on the internet may not like it, but until something happens in a more official capacity than an internet forum, that’s the truth.
Because of his plausible line to the British monarchy, it would likely be expected for political expediency (but likely not mandated) that he would formally renounce his British citizenship and place in the royal lineage through an official act with the British government like a letter filed through the British embassy. Since the US can’t dictate foreign laws, if the Brits decide to ignore that letter and keep him in line for the throne and allow him to hold a British passport, all the US could do is refuse to recognize it.
Until such a case is made and proven otherwise in the Supreme Court or resolved through an act of Congress or Amendment to the Constitution, that’s the only burden of proof that has to be met legally. Everything else is internet speculation. Of course, if he turns out to be a conservative and looks like he’d be heading for a win, all bets are off.
Best answer yet and most thorough. Thank you
Let me throw a wrinkle in... Foreign Emoluments Clause...would that apply since he’s in the Royal Family?
Can a person both be naturalized by act of Congress, and a NBC?
Rogers v. Bellei. Congressional act conferred citizenship at birth. SCOTUS considers this to be “naturalized by statute.” Absent a Congressional act, same person would not be a citizen at all.
What does age have to do with being a "natural born citizen"?
I was a natural born citizen the moment of my birth, and it didn't matter how old I was, I was still a natural born citizen at any age.
What is this strange sort of citizenship of which you speak that you must qualify for by reaching a certain age?
It sounds rather unnatural.