I believe that Bill Clinton said almost the same thing about 30 years ago, stating that he looked forward to the day when whites are a minority in the United States. Sadly, it appears that he'll be around to see his wish fulfilled.
Replacing white European stock with non-whites has been a cornerstone of the Democrats for decades for ideological reasons. Of course, until recently, most Republicans helped facilitate the process because of pressure from short-sighted business interests who want cheap Third World labor.
20 more years? Looks like the syphilis is chewing on him pretty hard these days.

Ten more years at the most.