To answer a question, if a VP becomes POTUS, that now-POTUS can choose to nominate a VP, to be approved by Congress. But there is no requirement that he/she do so. The Constitution is pretty silent on successor VPs. Case it point; Ford nominated Nelson Rockefeller as his VP when Nixon resigned. Rockefeller was approved by Congress and served as Ford's VP. However in the period following JFK's assassination, LBJ never nominated a VP.
The Speaker of the House is 2nd in line to the Presidency, after the VP. There is no line of succession to the Vice Presidency.
Thus endeth the US political structure lesson for today.
I don't think, barring a medical catastrophe, that Joe will resign. Nor should he, he can do the job. Having him in office not only continues his wise leadership and completes his legacy, it frees up Kamala to hit the campaign trail hard. If Joe were to leave office, she'd be 'stuck' in DC.
I thought Joe's speech was wonderful last night. He made it clear that he was resigning for the good of the Country, not due to any 'inability' on his part to carry out his duties. He also made it clear that it was a very difficult decision for him and was made after a great deal of thought, discussion, and I'm sure, prayer. A great Statesman.
And for those unfamiliar with the use of the phrase 'passing the torch to a new generation', it comes from JFK's inaugural address, and I've underlined the bits that I feel are particularly a pointed, but unspoken, warning to Trump and his ilk: "Let the word go forth from this time and place, to friend and foe alike, that the torch has been passed to a new generation of Americans, born in this century, tempered by war, disciplined by a hard and bitter peace, proud of our ancient heritage, and unwilling to witness or permit the slow undoing of those human rights to which this nation has always been committed, and to which we are committed today at home and around the world. Let every nation know, whether it wishes us well or ill, that we shall pay any price, bear any burden, meet any hardship, support any friend, oppose any foe to assure the survival and the success of liberty.”.
JFK was 43 at the time of his inauguration, out-going POTUS Eisenhower was 70, a virtual 'spring chicken' by today's standards.