Some of the automobiles that I restored still had working tube type radios. With today's electronics I would think that vehicle radios should last forever. I know that the current TV's are much more reliable than those a few decades ago.
I am guessing that most of the failure comes from mechanical issues caused by the constant earthquake environment that our motor homes endure. Components that are shaken loose/damaged are the main causes of failures. I don't think the same quality exists in aftermarket radios that are used in most RV's.