It doesn’t take nearly as much as they make. You can tell by the ease with which they throw around billions to expand the empire. Their income isn’t going to fall dramatically. People move on quickly. Especially when you’re dealing with a many faceted empire like Disney. Only the most dedicated Disney hater can remember ALL the tentacles and boycott the whole thing. Most folks have stuff to do besides remember every little piece of a corporate empire.
It doesn’t seem that hard. Avoid: ABC, Lucasfilm, Disney stores, Disney films, check items you plan to buy for the Disney label, etc.