I have been a long advocate of replacing the 5.56 while in the Marines, and even more so once I started shooting NRA High Power Rifle. It was not uncommon for those of us shooting factory match grade 168grn .30 rounds to shoot better scores at the 600yrd line then those shooting 5.56 handloads atop compressed charges and VLD bullets.
Saw the limits of the 5.56 in rural Afghanistan. There was a reason why the insurgents attacked from elevated positions, with PKMs, RPGs in the main effort, and AKs in the harassment/security role. They knew the limitations of the 5.56 round.
The M2 and MG240s (my personal favorite), got the most effective use. M16/M4 were just wasting ammo. You use a MG240 in the suppressive role while the riflemen advance with "I AM UP! THEY SEE ME! I AM DOWN!" advancement or flanking maneuvers.
The US Army spent a lot of money to over come all the deficiencies of 62grn "green tip" with the M855A1 EPR round. A lot of money. And, only to replace it with a better round in their next generation weapons systems. Again, according to the Defense Acquisition Cycle, the contract award goes to the candidate that met the most requirements, at the lowest cost.
Based off his posts, I think I would rather have a platoon of Arcticdude like riflemen (i.e. "riflemen" definition per the late, great COL Jeff Copper) with bolt action 30-06 rifles whom have a 90% first hit rating than a platoon of yahoos with AR15s and a 1 in 10 hit rating post-SHTF.