Its great to see this thread has legs. I have not sold off the 4x5 equipment yet but am shooting with it less and less.
Since my OP I have had to check my mother and father into a nursiing home and that gives me an erie look into the future for myself. Also some strong motivation too. Like tomorrow I will take the Nikon 300mm and the N90s out to a hill over an area I have seen deer in early in the AM. Hope to see some and send prints down for mom and dad to see. (dad would probably tell me to not use a Nikon but a 30-06 to shoot a deer)
A lot changes with our bodies over time, I hope to keep adapting and still enjoying photography.