Ah, OK now: I thought you were talking about the M855A1...
Yes, I fully agree at the moment:
the 5.56mm NATO, along with the 7.62mm NATO, will be used at least for the next 10-20 years!
Both are very accurate, with the 5.56 being smaller, lighter, slightly faster and in some cases more penetrating;
while the 7.62 retaining higher Stopping Power and longer Range!
The 6.5 is very accurate as well, but rather larger compared to the 5.56;
while the 6.8 having more Stopping Power than the 5.56, but less than the 7.62 and shorter Range than both the 5.56 and the 7.62...
Am I correct?