My father isn't a HN regular, but he's 70 and is very much a hacker. He founded a software startup (www.imatest.com) when he was 63, and now has a dozen employees and is working harder than ever as its CTO. His passion for hacking hasn't waned in the slightest -- if anything, it's increased by orders of magnitude since he retired from his day job. His hacking aptitude within his own narrow speciality (imaging science) also seems to be undiminished.

I do sometimes notice that the breadth of his hacking aptitude might be less than in a younger person; he doesn't always grok new concepts as quickly when they are outside his immediate area of interest. Eg., it took me a long while to convince him that automated testing was a really important part of modern software development. But I can understand how this would seem quite alien to somebody who first learned to program on punch-cards -- and since he's happy to delegate things beyond his immediate area of focus, it hasn't been a problem.

So, anecdotally: medical issues permitting, there's absolutely no reason you need to scale back on your passion for hacking passion as you age, although the breadth of your hacking might need to narrow somewhat.