The Mavic will win this round - I'm almost sure of it.
The technology they've managed to pack into that case is pretty incredible.
The P4 might actually have a better camera looking at the early shots, but the Mavic's camera is no slouch either.
The Karma will do well, especially thanks to the removable gimbal, but I don't think it'll be enough to stop people being drawn to the size and flying capabilities of the Mavic.
Good comparison between the P4, Karma and Mavic here - https://www.heliguy.com/blog/2016/09/26/dji-mavic-pro-vs-phantom-4-vs-gopro-karma/
I'd agree that the results speak to themselves.
I've spoken to a few people and they have all been really happy with their Osmo's.
A couple of them said they've enjoyed it even more after adding another battery and the LED accessories -> http://www.heliguy.com/dji/osmo.html