A real scary scenario is when an app no longer works properly with a new OS revision, and promises a fix that doesn't arrive for months.

Never mind a stale interface, or the fear you're no longer using the best app for what it does. It threatens to drop out of the "good enough" category.

That was Quickeys a few years ago. It was an automation app that I had used since the days of System 7. When Version 4 of the OS X version of Quickeys came out, it was magnificent, the best version of QK ever released.

About a year or so later when MacOS X "Lion" came out it, QK had some bugs in the new OS revision. A fix was promised. It never came. Then as time passed and my worries were switching to questioning compatibility with the upcoming OS X "Mountain Lion", it was revealed that the publisher of the software, Startly, didn't do its own coding, but contracted it out.

Startly apparently didn't keep close tabs on its contractor, because no work was done on it due to the contractor's illness. By the time we users were told of this, the contractor had passed away, and Startly was begging for leads for a new programmer, even offering a "bounty" to whoever referred the coder who would be hired.

It was at this point I realized that I could not rely on Quickeys anymore. It was too tightly integrated with the operating system be assured that Startly could keep up with the new annual OS release schedule.

I ended up trying a newer app, Keyboard Maestro, to replace QK.

I occasionally pop into the Startly forums to see if any progress is made. As of today (Tuesday, November 19, 2013), nope. Strangely, they still offer the app for sale. I guess Startly could be called a "Zombie developer": dead, but still walking.