Zemeraire
Songster
They would be whatever the base colour is.What will the other 50% be, white? What would their genetic make up be, assuming the paint parent does not have any recessive white?
If your paint is double extended black, then all will be extended black BUT the recessive white could have ANYTHING. So you could end up with all black or paint, or the white could carry something that modifies black such as blue.
If your paint has only one copy of extended black, half the babies will be extended black. So black paints and solid blacks, again with the potential for modifiers from the white. The other half will be a total mix bag. The paint parent might have genetics for non extended black as well as extended black, it might not. The white parent's base colour could be ANYTHING.
And again, if your paint is not extended black based black, it will pass on half of that mix to its babies and the other half comes from the mystery white parent. You may not even get any black based paints.
You could end up with blues, partridges, birchens, wheatens, barring, penciling, ANYTHING. It is totally up to what is under the white.