This project has been in the pipeline for years, and the concept (a general purpose round that has more reach than 5.56x45) will probably be outdated by the time it hits general issue.
The rifles look
HEAVY which implies a reliance on mechanised or airborne (probably helicopter) deployment of infantry.
Would think there would be lessons learnt after the time in the sandbox showing over-encumbered infantry is not a good thing especially when mountainous terrain comes into play.
The one true step forward in terms of infantry small arms was the Armalite AR15 and .223 Remington round to go with it, shame Uncle Sam had to intervene to save costs and get so many GI's killed in Vietnam (unlike the Brits buying the unmolested AR15 and .223 for use in Borneo and Malaya before the M16 became general issue).
The AR15 was a lightweight rifle which shot an extremely lethal round, proven by the fact that the Soviets came out with 5.45x39 in response (also an impressive round for military use).
However, the M16 has gone through a lot of changes, and I believe the M4 Carbine is now the general issue weapon in the US Armed Forces. It's become a heavier platform over the years even though the barrel lengths have gotten shorter. An interesting development was the MK12 Mod 0 SPR, a 5.56 designated marksman's rifle which was not general issue outside of SOCOM.
I suspect the 6ARC that Hornady developed with Department of Defense input (.308 ballistics which fits in an AR15 platform) will make the 6.8 SPC stillborn. I believe 6.5 Creedmoor is already being issued within the US Armed Forces, with M110 rifles being converted to use it.
More info on 6ARC here:
The US Army procurement system is bogged down by bureaucracy, by the time they get their act together, the product will either be so impractical to meet all the unrealistic parameters set out, or too expensive, or too heavy etc... look at the M24 rifle, long action Rem 700 for a .308, outdated optic (fixed 10x Leupold Mk4), ridiculously expensive due to unnecessary inclusion of target style iron sights and slow to reload due to a hinged floorplate
On the other hand, the USMC and their M40 program (pretty much a custom built rifle) evolved as they spent the time and money making it better.
I'm sure
@MarinePMI will be able to give you the true picture, unlike my armchair observations typed above.