I wonder if the blacks in the north US/europe in 10,000 years from now will automatically start to become white naturally.  What makes you think there will be any Blacks in America or Europe in 10,000 years from now?:D   And seeing as the Arabs and Caucasoids have been living in places like Arabia, northern Africa and mesopotamia(Iraq) for many thousands of years, regions that are hotter and sunnier than sub-Saharan Africa, and still haven't become Black I am doubting that evolution works that way.