If a Vice President can’t (or doesn’t) finish their term, the President gets to select their replacement. No vote required. He can pick anyone. Then if the President dies (or resigns), the new Vice President becomes President. It is unlikely Joe will finish four years. Chances are they will get rid of Kamala before he quits/dies. Anyones guess on who replaces her.
New Vice President must be approved by both the Senate and the House.
"Suit up, Huma. We're moving back to Joint Base Swampy!"