We change physically as we age, eyesight, steadiness of hand etc but also in temperament. If the Leica no longer works for you it's not that big of a deal. My eyesight is worsening as I approach 50. I'm still able to use my Nikon FE just fine but there are times when I struggle a bit with my eyes and manual focusing using the split prism. Also, like your Leica, there is no real grip on the FE. So I picked up a Nikon F90x dirt cheap in great shape and the autofocus on that is very reliable and there is lots of grip. Just use a camera that works for you and enjoy yourself, life is too short to fret over a particular camera (yes even a Leica).
When I was younger I loved driving stick, and I would scoff at automatic transmissions. I would hate to have to drive stick now, especially in traffic, my aging knees just don't need that kind of work. Such is life.