Tactical Life posts that the military is changing to the 6.8 in SAW and M4

[montana]

Look, here is the idea

6.5x39 (Grendel) would work with current M4 weapons requiring only a barrel and bolt swap.
6.5x45 would require a new rifle but is close to idea.
6.5x51 (260 Rem or 6.5 Creedmore) is too big

Not seeing the 6.8mm as anything but a compromise.

Also the .338NM (8.59x63 vs the .338LM/8.59x70) would make a good replacement for the 7.62x51 in the M240 series of MG

As much as the Grendel bolts have improved, I doubt they would measure up to military standards. It would probably take a redesighn of the AR upper and lower similar to the LWRC SIX 8 and a similar proprietary magazine.