Autopilot 2.0 and 100 kWh pack. Possibly also a small performance hike. IMHO.
Edit: Actually, scratch that. Probably no Autopilot 2.0. Just the 100 kWh pack and possible increased performance. (Autopilot 2.0 is likely to get it's own event, or be revealed as a part of the Model 3 reveal part 2.)