[juanbenae]

Looks to me like it split one time before where the two 4" branches are now growing from starting the trunk rot. It's a goner in my estimation. Maybe cut it to ground level and see if the roots will send another stock or two out next year and see if you can get it restarted that way.

When I drive through the central valley there are a bunch of walnut orchards that are grafted trees with the bases/root system being a species that is less susceptible to rot, and the fruiting portion is another species that produces better and more nuts. If I recall the stump/root portion is a Black Walnut and the fruiting portion is a much lighter barked type. They still have a specific life span and you will often see whole orchards fallen and being removed. There are signs around too that advertise orchard removal services.

Fruit trees defiantly have a life span that is not forever.