Also, consider single performer vs. multiple performers. There were a few people that helped in what Shari Lewis did, but not nearly the scope. There was really no one to carry on. Factor in what SK and Vic said and the dream just dies.
Shoot, if JHC passed with Jim, then look at the amount of assets that would have to have been re-organized and distributed. Same thing with Henry Ford or anyone that has dared to make it big. What would have happened to the Walt Disney corporation in 1966 if it was just well known but not hugenormous?