The M1 airs were available for sale as recently as march of 2024, so you have at minimum another ~3 years of replacement parts availability ahead of you. The timer starts from the last offering for sale, not when you bought your computer. Software updates might be more limited, we'll have to see. 6-7 major updates is about average for the Airs[2], but 8 and 9 isn't unheard of either and we're already at 7 for the M1s
They were however right about one thing, out of warranty repairs are only warrantied for 90 days from Apple.
[1]: https://support.apple.com/en-us/102772
[2]: https://en.wikipedia.org/wiki/MacBook_Air#Supported_operatin...
With Linux, a device can stay snappy far longer than Apple provides updates to MacOS. That's why my personal computer is old Thinkpad, I can thankfully use work-issued Mac for anything that requires more power.