I care too much about thinking about logic and systems and care almost not at all about thinking about people, which is what those other roles entail. Let me ask you this, how does changing your role change what you're experiencing?
IMO you'll learn more of the math than anything, unless you take some embedded systems track. An embedded systems track will get you working closer to the metal.
No idea what you're talking about. I've worked with devs in their 40s and 50s. Looking at an ex-coworker in their 40s now who just got a senior position at paramount.