As you said times have changed. Not all races stick to there own, I guess it takes one person to break the ice to form great inter racial friendships.
As for what I would do? well i would want my child to interact with other races. But thatws something you and your DH have to decide together ( i know you already know this)..
If you think that your child will be better off in a mixed race day care, then stick to your guns and make that happen, if you want your child to be in a all white day care, than do that too..
I dont think it really matters either way with day care, its more when they get to school age..
Hope you work it out