it depends on whether or not the breed is co-dominant but even then it may just be gray. try it out and see what you get, try breeding black with other breeds, and white with other breeds. which are you trying to breed?
chances are they will end up splash or some other unpredictable color. they could also possibly turn out either black or white, which i think is more likely.
i would continue breeding chickens, keeping track and maybe create you own variety of blue! possible also breed blues with different colors
i say experiment!