MacBook Air gets hosed, other models hold steady in macOS 15 as Intel support fades

Before we start visualizing things, here are the high-level takeaways. These haven't changed all that much since last year.

• For all Mac models tracked, the average Mac receives about 6.6 years of macOS updates that add new features, plus another two years of security-only updates. The 2018 and 2019 MacBook Airs are under this average, with 5.8 and 5.2 years of macOS updates, respectively.
• The average Intel Mac receives about seven years of macOS updates and another two years of security-only updates. So far, all Intel Macs released since 2016 have come in under this average.
• The average Mac receives updates for about 5.5 years after Apple stops selling it. Buying a Mac toward the end of its life cycle means getting fewer updates, especially if it's much more than a year old.
• The 2018 and 2019 MacBook Airs are getting fewer years of updates than any Mac released since 2008.
• The three longest-lived Macs are still the mid-2007 15- and 17-inch MacBook Pros, the mid-2010 Mac Pro, and the mid-2007 iMac, which received new macOS updates for around nine years after they were introduced (and security updates for around 11 years).
• The shortest-lived Mac is still the late-2008 version of the white MacBook, which received only 2.7 years of new macOS updates and another 3.3 years of security updates from the time it was introduced. (Late PowerPC-era and early Intel-era Macs are all pretty bad by modern standards.)

Compared to last year's data, some of our numbers have shifted a couple of months in one direction or another since we now know the dates of the final security update for macOS 11 Big Sur and the final non-security update for macOS 13 Ventura (we had previously extrapolated those dates based on Apple's prior behavior). We continue to use extrapolated dates for currently supported macOS versions, assuming that each OS releases in October, receives non-security feature updates for about a year, and receives security-only updates for about two years after that.

Some charts

Normally, we track Mac support by release year since Macs across all of Apple's product lines have essentially been supported or not supported in lockstep. But Apple has only discontinued one Mac apiece for 2018 and 2019, and looking at those numbers now would be a bit misleading.

For reference, here are last year's charts, which track all Macs released between 1998 and 2017. The gigantic dip in the middle is the transition between the PowerPC and Intel eras; the peaks on either side of it represent the heyday of the PowerPC and Intel eras. The smaller and more gradual downward slope that starts around 2013 or 2014 represents the start of the Apple Silicon transition. On average, latter-day Intel Macs are getting between one and three fewer years' worth of updates than they were at their peak, depending on which model you're talking about.

I've also put together some speculative versions of those charts that assume Apple will end support for all Intel Macs next year in macOS 16. I'm not sure whether this will happen, but the extrapolated data adds some context to our discussion.