The engine will last but the coach isn't worth it

When we were going cross country with our 11 thru 17 year old rig I would always walk the parks and see how many older rigs had out of state plates. Most the time I was the only one, or maybe there would be one or two others in the more popular places.

I think it is mostly psychological, the older the rig the less likely the owner is to venture far. Those that do carry enough tools (and know how to use them) to rebuild just about anything both mechanical and house.