In the next few years, I'm planning to go to 60% or 80% time, and then, eventually, to taking at least a couple of years off from engineering relying on savings

In the next few years, I'm planning to go to 60% or 80% time, and then, eventually, to taking at least a couple of years off from engineering relying on savings and my spouse. If I thought I had to be a line engineer making things for someone else forever, I'd probably have to quit just to regain some sense of control. It's good work if you can get it, but it won't be my forever.