The Takeaway: Mountain Lion support likely to end this fall
If Apple continues its previous practice, users of Mountain Lion can expect to receive the OS's final security update in mid-September, a month before the expected launch of El Capitan.
Mountain Lion, the last of the cat-named systems, debuted in July 2012, and Apple charged users $19.99 for the update. Apple dropped that practice after Mountain Lion and now issues its newest OS for free.
Apple appears to provide support for three OSes at a time, and the arrival of El Capitan, presumably in October, will push Mountain Lion into retirement. The other two supported systems are Maverick (OS X 10.9) and Yosemite (OS X 10.10).
Unlike other software vendors, Apple doesn't reveal its support policies, so there's no guarantee on Mountain Lion's support retirement. Based on previous Apple practices, here are some of the reasons it's likely:
Meanwhile, users running Yosemite can expect in September to receive that OS's final non-security update, which fixes bugs, improves reliability and performance, and possible includes new features, just as the plug is pulled on Mountain Lion.
With reports by Gregg Keizer at Computerworld.