It'll be called Time Zone, or maybe Twentieth Amendment, and it will revolve around the provision that "The terms of the President and Vice President shall end at noon on the 20th day of January." An international incident on inauguration day triggers a constitutional crisis revolving around the fact that the Amendment doesn't tell us what time zone will be the reference point. The old President decides that when the new President is appointed in the Eastern zone, the old President remains in charge in Central and points west, and then his power only ebbs hour by hour rather than vanishing altogether at noon Eastern. High drama ensues. Military forces from different time zones have a tense standoff. The Florida and Kentucky militias skirmish across the time line. Eventually the old President is reduced to staying in a bunker in the Aleut Islands, commanding the tiny remnants of the nation that he has left. It'll sell millions, I tell you, millions.
Great Idea for a New Legal-Political Thriller: