For all you guys freaked out by the horrid names on the “next in line” list — Relax, at least for now. The list cancels out when the Senate approves a new Vice-President, as nominated by whoever’s lucky enough to have made it to President.
A Secretary-of-Whatever makes it to the top not by waiting patiently and giving back-rubs (there are children reading this) but by lucking out when Fate (or SPECTRE) suddenly kills off all the others.
Tom Clancy took this and ran with it in one of his last novels. His favorite character, who’d been around since “The Hunt for Red October,” finally makes it to the top, though there’s not much left to be on top of.