I mean come on....there's got to be a 98.675% chance that Biden or Bern die before the end of their term....right?
So at the end of the day aren't Dems really voting the VP to POTUS at some point in the term...Seems a bit bizarre to think of it that way but come on...lets be realistic.
Trump could also die at the end of his first term and Pence could also die.
So if you want any age restrictions for what is the oldest you can run you would have to factor in Trump because he is over seventy years old...
Also it would take a Constitutional Amendment which is never happening with this splintered government!