Nonetheless, TDF 17 discussed the coming time when, under Heller, government arms will outclass and be inaccessible to civilians. It's possible this new round may mark the start of this. (NOTE: This seems less likely than before, but it is something to follow.)
CAVEAT: Things are still in development, and the 5.56mm and 7.62mm will likely remain in heavy U.S. and NATO use for years to come. It reminds yours truly of seeing a vast amount of .30 Carbine stockpiled by "survivalists" (the '80s term for preppers), despite its effective replacement by 5.56mm two decades before. But again, we shall see.
For more on the weapons themselves:
1. Army chooses Sig Sauer to build its Next Generation Squad Weapon (armytimes.com)
2. U.S. Army Announces New “Next Generation” Infantry Weapons (popularmechanics.com)
3. Brandon Herrara video:
MY COMMENT: Relative effectiveness is not the big issue in this. All three rounds are effective. Issue is interoperability with and use of military stocks by the 2A civilian Militia. In that vein, recall that decades after 7.62mm NATO was adopted, and then 5.56mm, there were still Guard units using M1 Garands in .30-06. Very likely that reserve components, which are the units in closest proximity to domestic civilians, may be using hand-me-down 5.56 and 7.62 for a long time. Ditto State guards and law enforcement.