All so often the popularity of a firearm, or caliber, is often equated with quality. I think this has to be true to some extent, because at some point an ineffective caliber or firearm prone to serious problems would lose the popularity.
For example, 9mm and 40 S&W. Both great calibers, however if they were not so commonly used by LE or the military, would they lose some of the luster? Hard to say, because a caliber fits a roll based on the needs of the shooter.
Now consider handguns. I don’t think I could be convinced the popularity of the Beretta 92F 9mm is not related to the M9 Beretta pistol. As a Glock owner, I must also admit, I don’t think the Glock would be as popular if not for LE use (vs. other polymers). However with the Glock, you do get a firearm at a completive price, no manual safety vs. those other polymers.
Now consider the AR-15 and the .223 Rem (5.56x45mm NATO) caliber. Is the appreciation artificial?
If the military were to switch to the 7.62x51mm NATO, would the .223 Rem (5.56x45mm NATO) lose the majority of its following. I imagine you would see fewer 5.56x45mm NATO rounds, but somehow I think .223 Rem plinking would continue. I think you would see an increase in the 7.62x51mm / .308 (and to a lesser degree 7.62x39mm) as the go to home SD round in a rifle, as the .223 / 5.56x45mm would begin to drop as a home SD rifle round.
So how about the AR-15, M-16, M-4. For example, would the AR-15 lose popularity if the FN Scar was selected as a replacement for the M-16 / M-4? I’m starting to think there is a bit more hype to the AR-15 due to the military cousins and LE usage. If no longer used by the military, I think cleaning and maintenance concerns for the AR platform would begin to take more consideration.
Note: I don’t think anything is likely to change given the econ and deployments overseas. I feel strongly about this when it comes to caliber. Advantages are minimal between the calibers being considered. The special forces community needs options, and those options can be provided in caliber, without changing the standard cartridge for the majority (in addition there are NATO considerations).
Gun rags / magizines have upped the conversation, but I see the critics point that the FN SCAR (MK16 / MK 17) is a bridging-the-gap solution, and for all the hype, is not truly revolutionary. I doubt there will be a massive switch do to funding. Still, the more likely change is the rifle, as the number of dust related stoppages could be related to troop morale. Sometimes the one thing that works from the bottom up in the military is the confidence the user has with the tool.