Someone who is "Black" is essentially someone who:
1. Is not [traditionaly] white;
2. Has origins in Africa.
(Yes one can theorize we are all from Africa, but let's not open that door).
This is Vijay Singh.
This is NOT a black man. He is certainly not white but has no direct ties to Africa. He is not black and is not African-American. He is Fijian.
Once you can distinguish between race and nationality and how they corelate with one another (In our society) you will understand how people are catagorized as such. I'm not an expert by any means but I am telling you how--for example, let's say a police officer--would catagorize someone in terms of race/nationality. If society (including the gov.) deems Obama black, then he is black. There is no way around it. After all, it is society that
created and enforced these labels.
To the OP: I think you have answers to your question within this thread. There are people at present who will argue that he is not black. Perhaps when a time comes that the black population of America feels he is not catering directly to their needs that number will rise.