2016 was full of interesting developments and new-ish type items developed for a more realistic threat.
First and foremost, expect 2017 to usher in shorter everything, especially in the AR-Pistol / SBR platform. Specific .300blk and pistol caliber AR15-Pistols. I have an 8" .300blk which I am building right now for the 75y and in range of application. There are people who are building 6" 9mm AR15-Pistols for the same application. CQB and "school/hospital hallway distance" is the name of the game. You will see more and more of these types of developments. Some will be PDW style like my PWS PDW SBR:
Expect everything, from rifles to pistols, get RMR's and Aimpoint Micros. You will also see more companies developing micro and reflex optics/RDS like the RMR and the Aimpoint Micros. Lots of pistols will be getting these attached to them and more people will be carrying them in that setup. Some with lights, some without. I am thinking that there will be a happy development through use and experience that ends up with a compensated gun which does not have a WML but has an optic. You will see a lot more Roland Special type guns but only one #voodoospecial:
Lots of aftermarket triggers like the Overwatch Precision trigger above will make their way into people's carry guns and that will start to become a standard thing. However, more and more people will keep their gun fairly straight forward, OEM barrel and good aftermarket iron sights, like those from Ameriglo:
Also expect older colors to come full circle, multicam will make a combat and multicam black (or other versions) will also begin to make room in the camo market. More people will start going away from kryptek type color schemes (as no actually employs them and they are 2-5x the cost of traditional camo colors). The SKD PIG Gloves are an excellent example:
You should also expect smaller boutique style shops to open up with very niche products that cover very specific things in the gun industry. Some already exist, like the taudevgroup who developed "The Gadget" for Glock CCW pistols.