I have an M1 MBP from Nov 2020 and semi-recently did a complete reinstall and setup as new and WHOH is it so much better.. I wasn't having performance issues really, but was having a permissions issue that needed a reinstall. It's almost like brand new again.. A 5½ year old computer. I tend to replace my computers every 5 years or so, but this has me rethinking things.
On my M1 MBP, I use Logic to record our band and then tend to have maybe 10 or so apps open all day beyond that just for daily use stuff. Then I have an M1 MBA from my work, they sit side by side, and the work MBA only runs a bunch of web pages and Citrix apps and MS Office, work stuff.. I see NO reason this MBA can't continue for years like this. Any "intensive" type of apps we use for our work are all through Citrix, so that's an easy one. It's only got 256GB of space, though, and I see our org's "you're running out of space" message via Jamf, but I still tend to have roughly 50-60GB's free when that comes up.
I think I'd be fine using these machines for years still, but software tends to be tuned more for current hardware as opposed to older machines. It'll be up to Apple, ultimately, on whether they think it should be supported still. I hope they keep these things going, though. No way I can afford to replace it! Not in this economy.