Unfortunately, I now expect Apple to drop all Intel support in macOS 16, which I am assume is coming ~ September 2025. It looks like Intel is dropping support for the processors used in many still-supported Mac systems after June 30, 2025:
Changes in Customer Support and Servicing Updates for Select Intel® Processors
www.intel.com
While I don't think that means Apple has to drop Intel support, I suspect they will. Even though they just sold some refurb Mac Mini 2018 a few weeks ago. Which means those buyers will get less than 1 years on a current OS and less than 3 years total.
There are still a few processors used in Mac systems not on that list (e.g. W-2140B as used in iMac Pro but that may be a special case not covered and similarly i3-1000NG4 as used in the MacBook Air 2020), but it's hard to imagine them dropping the Mac Pro (2019) while still keeping all the Intel support to keep the iMac Pro 2017, MacBook Air 2020, and/or MacBook Pro 2020 going.
If so, this will start the final countdown to Intel-based Macs becoming practically unusable. I project it would unfold like this:
-September 2025: macOS 16 drops all remaining Intel support; Sequoia last version of macOS that supports Intel
-September 2027: macOS 18 released; Sequoia unsupported; Intel-based Macs essentially unusable in the enterprise
-Winter 2027: major ISV (e.g. Microsoft) follow suit dropping support for Sequoia and therefore any need to include Intel support
-2028: Apple's releases new Xcode that requires macOS 18 but doesn't include Intel support
-Fall 2028: macOS 19 released; macOS 19 users have to use an Xcode that can't generate Intel code
-2029: any ISV still supporting older, unsupported macOS (e.g. how Firefox 115 ESR still supports 10.12 and Firefox 128 still supports 10.15) start to peal away -- having to stay on macOS 18 / previous Xcode or keeping a VM around becoming increasingly costly relative to the increasingly smaller user base
-September 2030: macOS 18 unsupported; no longer possible to run a supported macOS that runs an Xcode that generates Intel code; a few hobbyists and enthusiasts will remain but doubtful any commercial support
It's too bad as the above will also kick off my countdown to finding a new platform. I like my current Intel-based systems and sense that buying Apple Silicon will further lock me into Apple's ecosystem in a way I don't like. Don't get me wrong -- the M4 looks great (and I am sure its successors no worse) and I've liked macOS. Apple just continues to shift the platform away from the things that made me pick it in the first place, and I didn't sign up for the "walled garden". I've been holding out hoping it would reverse but the above would mean the end to my holding pattern. Granted I've had more than a 20-year run on MacOS X and that's not bad.