Uh, 1. Hispanic is not a "race" and 2. The Hispanic vote is 35-40% Republican, at least in Presidential elections. Hispanic Evangelicals voted for Bush by a margin of over 50%. Compare that to the blacks who voted under 10% for Bush last time.
If you really want to mess with his head, tell him that his assumptions are based on everyone staying within their racial or ethnic boundries in terms of marriage and children, which looks to be far from the case.