The only way it would get 500K orders is if it could somehow be actually made by Ferrari and not cost any more. Just slapping a badge on it wouldn't change anything. Car buyers aren't that stupid.
And the same goes for slapping a Cadillac badge on it. The only way that would work is if they actually built it with Cadillac amenities. That would cost more, and appeal to fewer people because of the increased price. You just have to look at the Volt to see how that turned out.