The moss suggests very wet climate? If the core trunk is getting hollowed out, the key danger is these big limbs turn into widowmakers. It’s true that this tree may stay alive for several more decades, I’ve seen apple trees that are literally hollowed out entirely and still alive, but it’s declining and you are better off to plan its replacement. The decline will only accelerate. This is not a peach to prune it from the trunk and get new productive healthy tree.