How could or should the 6.5 mm Grendel be improved?

[cory]

I think that would require a change in attitude among military decision makers, a change that IMO seems unlikely. Historical SOP has been one cartridge for individual weapon, sniper rifle, squad automatic weapon, and light machine gun. While that got a little mixed up after 5.56 NATO was fielded, necessitating use of two calibers, I just don't see them adopting 6.5 as a third caliber and keeping both 5.56 and 7.62 in the system.

It seems to me that the only way to get a new rifle/machine gun caliber adopted is as a replacement for one or both current chamberings.

While I share your view on the military mindset, an identical round used in a Infantryman's weapon and a Scout Sniper's weapon just isn't realistic However, a round that's interchangeable might be with the Grendel, IMO.