What are the chances this co-op ever will sell?

To answer the question posed above, I would say the likelihood is zero. The possibility isn’t even close to zero.  It’s zero.

This terrace, which is next to a schoolyard, shows up far better in a photo than in person.

The listing demonstrates beyond a doubt that any broker can fail to price, market and sell a property through sheer stupidity or greed. The stupidity would be taking the listing from an obstinate owner. The greed would be “buying the listing,” as in promising the owner a higher price than the broker can deliver.