To be honest I think any tech purchase will be obsolete after a number of years however you spec it. But it's not as bad as it once was...
I remember back in 1993 I bought what was at the time best PC I could afford for college - a 486DX 33mhz with 8MB of RAM and a 170MB HDD running Windows 3.1... It cost about £2,000 (in 1993 Pounds 😬) and I thought it was amazing.
Two years later when Windows 95 came out the poor old thing was just about on its knees!!!! 😆 Completely obsolete - what a waste of money!
I find it amazing that the MacBook Air M1 released three years ago at just £999 can in base spec still effortlessly run macOS and just about any "everyday" task most casual users are likely to ask of it, and is likely to for a good few more years. You can still buy them new - mine's been amazing value.
Is there any reason to suspect that M3 machines will have a shorter shelf life?
A 16GB machine will become obsolete the same day as an 8GB machine - it'll just be a slightly better equipped obsolete computer!!! 😂