Not sure how much of what's been released to the public domain so far will be proven accurate. When the 5.56 was first adapted and issued, there were all kinds of problems in the field, many related to the type of powder used to achieve the required velocity - it didn't work so well in a hot, humid climate. It took a long time to work things out, and even now there are differing reports from the field about lethality, penetration, accuracy, etc. Make one tweak (e.g., shorter barrel for convenience) and something else changes (reduced velocity) in the wrong direction.
Hopefully there's enough institutional memory in the military to avoid repeating the early mistakes made with the 5.56, but even with the newer "temperature stable" powders now on the market, I wonder how a compound case loaded to 80,000 psi will perform under varying conditions, especially as round count goes up . . . and up . . . and up.
And . . . I can't help but wonder if "green" mandates or even DEI considerations are playing some sort of a behind the scenes role in the round's development.