If past history means anything, I think Apple will drop support from macOS about two years after they stop shipping the last Intel model. The last Intel Macs (according to MacTracker) are:
- iMac (Retina 5K, 27" 2020), discontinued March 2022
- Mac mini (2018), discontinued January 2023
- Mac Pro (2019), discontinued June 2023
- MacBook Air (Retina, 13", 2020), discontinued November 2020
- MacBook Pro (13", 2020, 4 TB3 ports), discontinued October 2021
So that last Intel Mac (the Mac Pro) stopped shipping this past June. Or if you don’t think they’ll count that model, the next-to-last (2018 mini) stopped shipping this past January.
I expect Apple will include Intel support in macOS 15 (expected release, fall 2024, 1.5 years after the end of the Intel Mac Pro). I expect that macOS 16 (expected fall 2025, 2.5 years after the end of the Intel Mac Pro) will be Apple Silicon only.
Apple typically provides support and updates to macOS for about two years after release. So we can expect support for macOS 15 to end in fall 2026. And we can probably expect key apps (web browsers, office suites, etc.) to drop their support for the OS 1-2 years after that, with some holdouts lasting much longer.
So I think a recent-model Intel Mac probably has a useful life until 2027/2028, when important app updates are likely to stop. And people willing to be selective about what apps they expose to the Internet may be able to get several more years beyond that.
I wouldn’t have a problem with it. Assuming it has enough storage and RAM for your usage, I think you should expect Apple software updates for another two years (until fall 2026, maybe a little more if there’s a really critical security bug), most third-party software updates for about four years (until some time in 2028), and remaining useful for a few years after that.
You may need to replace the battery once or twice between now and its practical end-of-life, but that’s not too bad. According to iFixit an aftermarket battery costs about $120 and it is moderate difficulty (1-3 hours work). Or if you go to Apple, they will charge $250, which sounds perfectly reasonable for a genuine battery and the fact that they will install it for you.
But of course, everything here is speculation and could prove to be wrong.