Line-of-business software: 5 years after graduation. There is such a low ceiling in terms of skills and compensation that people begin to lose respect for you if you are still working on that stuff. Those problems are boring and the only reason to work on them is to move into management… which not everyone wants or is suited for.
High performance corporate infrastructure: you get 15 years. I’m talking about the problems Google and Amazon face. You’re still working on “what the business wants” but it’s more respectable, because there are serious challenges. Still, you’ll run out of new things to do after a while and want to become an executive just because it’s easier than competing for the rare project that can hold your interest once you’ve been doing this for long enough.
Research: no hard limit. Some people are still contributing to their fields in their 60s and 70s. There’s still a tendency for people to move into more of a leadership or mentorship role, but it’s not required. The main issue here is that there are so few basic research jobs out there that, once you get one, you do everything you can to hold it, which keeps you tied to one institution and geographic area. Doing jobs and doing them well gets easier with age, but getting jobs—selling yourself—is still a young man’s game. By the time you’re 50, you don’t really have the energy to sell yourself for 8 hours straight, nor hide your contempt for having to do it… you just want to get the work done, get it done well, and move on.
However, I do miss the exploration and the learning side of things. It's been a while since I felt like I was developing skills and exploring interestring things through my work. I feel like i'm looking for some kind of really interesting idea or new thing to explore or to make a career pivot into.
So, I've given thought about about maybe moving onto some position where I can feel the adventure of the new. I considered joining the navy ins ome kind of tech role... it still does appeal somehat. Though, it's a lot to just decided to do when you're almost in your mid-30s.
I'm in my early 40's and I think I will be doing what I do now until I retire (in whatever form it will be done, and if I'm not hit with brain desiese).
I've never been very thrilled about shiny shiny for its own sake, but I've been a poster boy for at least one major technology that you'll have heard of.
I'm part time on my research to try to keep my hand in with new tech and start-ups.
There are no fixed ages: it's a matter of interest and intent.