If we do, under the present designation, it'd follow the M1, the early 105mm main gun Abrams, followed by the M1A1 with the German-designed 120mm smoothbore main gun, then the improved M1A1 and M1A1 SEP versions. So the more likely designation would probably be M1A3. And that would also avoid confusion with the M2 Bradley Infantry Fighting Vehicle.
Of course, it's also possible that a remotely operated or autonomous tank, as envisioned by the late Keith Laumer about three decades back, may come along, known as *BOLOS* in tanker-speak, officially Unmanned Ground Vehicles or UG-Vees.
They're already using converted M60 and M48 chassis, remotely operated, as mine clearance vehicles. And the Black Knight is another remotely operated/autonomous combat vehicle under study 