At this point I have no doubt. Maybe with a couple of new justices it could be correctly defined.
The reason why those born a dual (or more) citizen are precluded from eligibility for POTUS via the natural born citizen clause is because the Founding Fathers correctly recognized that the foreign country has the valid legal right to assert their country's laws upon the born dual (or more) citizen individual at any time regardless of where they are, worldwide.
Prime example: the U.S. citizens impressed into service for the British Royal Navy in the early 19th century. Many if not most of those men were born in the U.S. to a parent (father, given the historical era) who had been a British subject at birth and were therefore dual citizens at birth. They were subject to British law even if they had never left the U.S. The UK has the legal international right to enforce their own laws on their own subjects/citizens, worldwide.
The US State Dept to this day warns about this very same problem afflicting any and all who were born dual citizens or later become dual citizens at some point in their life:
"Each country has its own nationality laws based on its own policy. Persons may have dual nationality by automatic operation of different laws rather than by choice.
...The U.S. Government recognizes that dual nationality exists but does not encourage it as a matter of policy because of the problems it may cause. Claims of other countries on dual national U.S. nationals may conflict with U.S. law, and dual nationality may limit U.S. Government efforts to assist nationals abroad. The country where a dual national is located generally has a stronger claim to that person's allegiance.
However, dual nationals owe allegiance to both the United States and the foreign country. They are required to obey the laws of both countries. Either country has the right to enforce its laws, particularly if the person later travels there."
http://travel.state.gov/content/travel/en/legal-considerations/us-citizenship-laws-policies/citizenship-and-dual-nationality/dual-nationality.html
What happens when a foreign country similarly impresses a born dual citizen POTUS into service for them, as they most certainly would have the legal right to do under international law?
That's what the Founding Fathers were trying to avoid with the 'natural born citizen' requirement. They wanted POTUS to have no split, dual, or otherwise compromised/competing allegiance from birth to prevent that possibility.
Pretty simple, really. And extremely reasonable to require a POTUS and the Commander in Chief of our military to have 100% allegiance to the U.S. from birth, with no competing/conflicting foreign claims on his/her allegiance or service.
To be clear: the problem is conflicting/competing allegiance at birth via dual (or more) citizenship, and a foreign country's valid legal right according to international law to enforce its laws upon its own citizens/subjects, worldwide.
Renouncing a citizenship with which one is born is iffy. In times of war or conflict, that renunciation may not be recognized. That's what happened in the early 19th century to U.S. citizen men born in the U.S. to parents (fathers, given that historical era) who had been born British subjects before the U.S. gained independence. Even though those U.S.-born men had never stepped foot in England and had been U.S. citizens all their lives, the UK had the legal right under international law to impress them into service in the British Royal Navy because they were the progeny of those who had been born British subjects, and therefore were also British subjects themselves under British law.
That aside, it's shocking that so many are on board with ripping the Constitution to shreds on more than just this issue (e.g., at the very least, the First, Second, and Sixth Amendments are also currently under attack: publicly speaking critically of Muslims, gun controls/bans, No Fly list compiled without due process, etc.).