I suspect the 6.8 is here to stay because ceramic personal armour penetration ( not just range extension) is the reason 6.8 is selected. You can see in the Video Karl was choking back the comments the last second on camera, multiple times. The rapid acquisition of HK417 as the SDM is to put armour penetration capability into the hands of the soldier, all these actions are related to general armour distribution amongst Russian troops and the Chinese is not far behind.
The other piece of the NSGW is the optic - Votex and L3 are the contenders. It combines LAD, automatic adjustment and others into one package. If all these are combined to together, I guess they are hoping to achieve and exceed what the USMC is doing with the M27. More accurate first hits and less bullets downrange. This will makes sense because automatic rifles are not supposed to be the same as light machine guns - one is mostly a point target wpn and the other is mostly an area wpn, but for years the US uses a LMG platform to do both. So it is kinda flipped to the other side now, it looks like the US is open for an automatic rifle that may do some LMG works.