Not for the kind of battles our troops are engaged in. The 5.56 is fine for European theater warfare, less so for urban combat.
Troops in Iraq regularly report that while shooting at cars that run checkpoints that 5.56 rounds fail to penetrate sufficiently to stop the car.
Additionally, troops in Afganistan report that shooting an enemy at 500+ yards with a 5.56 often ends up with the target going down and then getting back up.
5.56 is fine for an area denial weapon, ie keeping the enemy's head down while riflemen move into killing positions. It's not so fine as a primary infantry rifle.
Let's put composite stocks on the M14 and issue that as the primary rifle until we get something better.
"Troops in Iraq regularly report that while shooting at cars that run checkpoints that 5.56 rounds fail to penetrate sufficiently to stop the car."
That's what a 25mm Bushmaster cannon is for :)
They can also issue captured AK-47's until the shortage is made up.
Also, the Russians are going over to a 9X39 mm round, and have also built a modern AK-47. They found it better than the round being used for AK-74.
The engineer in me is screaming out.
That the M16 does what it was designed to do and doesn't do what it wasn't designed to do, should not come as a surprise.
Just as the old saying goes, don't take a knife to a gunfight; one doesn't take ammo/rifle designed to wound/disable people and expect it to do a good job at anti-material targets.
For checkpoints & road blocks, an M-2 in 50BMG is appropriate to stop a large truck. A 5.56 M14 or a 9mm pistol should not be expected to stop a truck or car. They weren't designed to do that. A 50 BMG was designed to stop a truck/airplane or blast through a wall.
People got to understand that you shouldn't expect to be able to drive nails with a flyswatter. Use the right tool for the right job. If the military commanders aren't smart enough to issue the right gear for troops to do their intended jobs, then court marshal the commanders.