We have Iran, Syria, and North Korea in the next few years. Do you we have time to make a major logistic change in time to fight these conflicts. To suggests that the 5.56mm is inadequate is rdiciulous. The Israelis use it, in fact, the weapon that OBL carried, or carries, fires a 5.45mm round.
If you were ever actually in a fire fight you wouldn't make such ignorant statements. The Israeli infantry actually use and prefer the FN FAL which is 7.62 mm and the UZI which is 9 mm. Lastly, OBL was never in a fire fight. He uses his weapon as a fashion accessory.
The Russians have been developing a new round and went back to using 7.62, and the Chinese have quit building QBZ-95 rifles with 5.8 ammo because of our problems with the 5.56 ammo, and their problems with their small caliber weapons.