It's a shame. But having watched a few companies shut down APIs (including my own work at Google) I've learned the hard way that unless an API is central to a company's business success, it's eventually going to become a business problem.
I believe this is the appropriate concern. If your business would critically fail with no alternatives should a supplier back out you have a major problem, this same lesson applies to most any business.
Don't build a business on an API whose backend you cannot change at will.
Same goes for protocols (Facebook Login vs OpenID), format (DOC vs ODT) and data sources (Gracenote vs MusicBrainz). If you cannot replace a service that is behind an API with your own implementation, you must be ready to fold your business the day your provider changes the service terms.
