as long as that job keeps you up-to-date with the current state of the art? That is of course the crux. If you're the person that knows how the old stuff works

as long as that job keeps you up-to-date with the current state of the art? That is of course the crux. If you're the person that knows how the old stuff works (because you where there when it was the new hotness), you risk being responsible for the old stuff, while the new guy they just hired gets to work on the greenfield Rust project they just started. Had a friend of the family who spent his entire career at a Fortune 500 company. Started programming their back office mainframe systems in the 80s and spent the rest of his career working on those same systems. He knew those systems back to front and was revered as the local mainframe guru. 2002 he lost his job when the company decided to retire that old system and move on to something else. He could not get hired anywhere and ended up having to take a job a petrol station for while.