M1 owner and looking to upgrade to M4. I somewhat disagree, though I did go with the 8/8 16GB version so I'm sure that's been a good contributor to the longevity. And my use case is likely different from yours if you had the Pro with the Max processor.
I get money from work that I can use towards a some tech stuff and it's "use it or lose it". If the Ultra 3 was out, I'd be buying that instead, but since it's not I'll likely replace my M1 Air with an M4 Air. If I wasn't given that money from work I'd wait for M5. Maybe even M6, but it depends how the Apple Intelligence tax pans out as they continue to add functionality. I know, I could disable it, but I like the features so far, as imperfect as they are.
Not suggesting that someone buy an M! today, but they're still ridiculously capable. I'm really surprised. Apple Silicon has been great.