"There could very well be someone half (Sanders) age in Vermont who could do a better job but is unable to raise the money to run for office or command voters’ attention as a relative nobody."

And who from Vermont could help this person to raise money and get voter's attention? A nationally known progressive politician could pull a lot of strings to help this young person become popular and electable, but what's in it for them? How can a younger, possibly more attractive and dynamic politician on the team make the older one look good? I don't think they can, and if the older politician decides to hold office until they die, a person like that could be a threat to them.