There is some really wild speculation going on here! A wagon/crossover? lol that's a completely new car.
Based on tidbits from what Elon has already divulged in his tweets, part 2 will almost certainly involve a revolutionary steering "system" and an amazing HUD, perhaps even holographic.
They're also *very* likely to announce much more advanced autonomous driving capabilities, aka autopilot 2.0, with possibly a suite of new options...i.e. summon 2.0 - the model 3 will open your garage door, exit, close the door, but will now be able to drive a short distance on its own to go pick you up... and autopark 2.0 - upon request, the model 3 will actively seek out a parking spot; upon finding one it will stop itself accordingly and park.