Finally they come up with something which has a distinct advantage over the old 556/M4.
Many of the suggestions in the past would have cost a lot to implement but not afforded and true advantage.
This new cartridge and rifle combo does provide an advantage.
Specifically, body armor. Everyone has it today. Heck, 21 years ago in Iraq ~ 1/4 of all the Iraqi troops had it. Today if you look at Ukraine, practically every Ukrainian and Russian have advanced hard plate armor...
The old 556 was great in a world where people had no or at most soft body armor. It’s time is already past!
Next, we need to replace our 9mm. While it might be a bridge to far to expect a short barrel, small cartridge to punch through ceramics and uhmwpe, at least we should address the soft armor which can be defeated with smaller, higher velocity, better shaped, and hard/laminated type penetrating bullets, say something like FNs: https://en.wikipedia.org/wiki/FN_Five-seven
The proliferation of more advanced body armor has changed everything.