The 22nd amendment, the one that bars him from running for a third presidential term, also bars him from running as a future VP. Legally he could be speaker of the house, or another high ranking unelected official, but he’s not inclined to follow laws anyway. Before Musk I would have said he wouldn’t want to be 2nd-in-power, so I would have thought having one of his sons hold a higher office than him wouldn’t happen. Everything is upside down now, so who knows what will happen