The 5.56 isn’t going anywhere.
Poland, Bulgaria & Croatia have current 5.56 compatible rifles and Romania’s newest rifle will be in 5.56 as well.
There are always going to be those who want a bigger & “better” slug to lug around. You trade off several advantages & disadvantages when opting for bigger or smaller.
The artile has a link to the new 5.56 M885a1 round.
Click the link.
From a standard M4 platform at a distance as short as 12ft, the round will yaw and create a 4.5in cavity through 14 inches of ballistic gelatin.
That's plenty, I don't care who you are.
Will also pierce 3/8in armor plate at 100yds. Or a concrete block at 40yds.
There is absolutely nothing wrong with those numbers.
The only thing lacking is RANGE.