Agreed, the appaloosa part of the sire is actually the pattern, we'll need to know his base coat color to form any kind of guess.
Just from the pictures, though, it looks like he may be black, brown, smokey black, maybe even grullo. Those foal coats are so funky because they very seldom seem to truly resemble the color that they will grow up to be.
He could end up being a leopard coat pattern. My black mare was born black.
He could be bay brown . I have seen solid brown /black foals end up as leopard appy's. Jusst have to wait and see ;) specially with Appy, as they can change every year .