We are yet to see for how long Apple is going to support their Apple Silicon machines, but this definitely sets a precedent for Apple. It would be really shameful if they go the iPhone route and cut support after 6 years of updates.
On the other hand, Apple is still selling the iMac with a 2020 chipset, so we could say that they look like they are committed to providing updates. I hope they wouldn't just cut off support in 3 years time.