I don't work on a server team, but in network/network security. My company made an announcement that they are extending our product's software lifetime to four years: 3 years standard support + 1 year high sev patches.

It seems to me in the 2020s that 5-7 years is plenty of support for a single OS release, and that OS support teams should be nimble enough to roll out new instances and migrate data at that cadence.