There is a two part test to be eligible to be present: You must be “natural born” and a “citizen.” Yes, if you are natural born you cannot obviously have that revoked. However, you can lose citizenship.
For example, if you are born in the U.S. but then renounce your citizenship, you are thus ineligible to be President. That is the issue with the Indonesia passport/adoption circumstances, not whether he was natural born.
Obama was a minor and was he Indonesia between the ages of 6 to 10. There is no way he could renounce his citizenship.
Can you also be born on foriegn soil to a US citizen to qualify as "natural born ?