Wait for the 17 models.I'm still with my 15PM, and still indecise if changing or not. But I think I'll wait for next one.
Any relevant improvement on camera shots image quality over the 15PM? That's the only thing on I could fall...
With all three camera lenses upgraded to 48 mpx this will be a way better upgrade. 15 pro to 16 pro would be a waste of money.