I'm 39 and write code every day for my employer, but outside the scope of the engineering team. I guess it may fall under exploratory/architectural work for what might be future products, though if they gain any traction they will move into the engineering team, and I move on.

I guess this falls under the "more and more senior as a developer", but I'm outside the direct line of fire of bugs, deadlines, etc.

I can't complain, and I'm often working on newer technologies than the folks in engineering, keeping my relevance.

My plan will probably to migrate into a consultancy.