Sure they coexist now, because, as sibling commenter pointed out, while outside of corporations market forces exist, every corporation or government entity itself is a separate world, where most of free market rules do not apply. Most of them are centrally planned in one way or another
Ok, I think we need to define what "central planning" means for people who are going to choose to participate in this discussion.
"Central planning" means "the government (or some other single entity, but usually the government) makes all of the decisions in the economy."
Corporations, despite being "centralized," and despite engaging in "planning," do not meet the definition of what we're talking about when we say "central planning." They emerge in a free market economy in order to reduce the transaction costs that would come with trying to coordinate mulitiple people as independent participants to do some specific activity. They do not exist to decide for the entire country exactly what everyone will be doing all the time to meet the entire nation's needs. That's a very big difference.
