The POTUS eligibility issue is whether there is dual citizenship at birth from a foreign citizen parent or by being born on foreign soil, not dual citizenship aquired as an adult or from a previous citizenship of a parent or grandparent. SCOTUS has only ruled that there is “no doubt” that the child of two US citizens born on US soil is an NBC. SCOTUS has only said there “is doubt” over the child of only one US citizen parent and foreign parent born on US soil.
The founders were fully aware that other countries, like Britain, could claim as subjects the blood children of former citizens (War of 1812 fought over impression of US NBCs claimed as UK subjects) but appeared to disregard that type of dual citizen from being qualified as NBC (nearly the whole USA in 1800).
After reaching majority an NBC can obtain foreign citizenship in some cases without renouncing US citizenship and thus an NBC can become a dual citizen as an adult, but that has no bearing on NBC POTUS eligibility, which is a condition of birth that cannot be altered.
The Congress has decided that a person born on a military ship or military base to two US citizens is a natural born citizen. Meaning if you’re on that Navy (or Coast Guard) ship in Canadian waters, and both your parents are US citizens, you are a Natural Born Citizen. And you also hold Canadian citizenship.
Look, the issue is you’re trying to restrict a person’s eligibility based upon what a 3rd party (another nation) decides to do. If the UK considered you a citizen, and granted the full rights thereof, are you suddenly prohibited from being President? NO! Because you haven’t renounced what you originally had.
The issue of dual citizenship is irrelevant, and is a serious distraction and bad avenue of argument over President Obama’s standing as a natural born citizen. None.