No-one suggested that the personal weapon for infantry soldiers will change anytime soon from 5.56. There's a host of reasons for that. However, there will be (and already have been) changes to specialised weapon platforms such as sniper rifle platforms, because there is recognition that for years now NATO has relied principally on two platform types for sniper use: The first is 30 cal (.308 Winchester) for short to medium range (to 800m) and the second platform being HME calibres, including 50 cal, .338 Lapmag and .408 Cheytac for example. The latter 3 all include for long range (800m to 2300m) anti-personnel and hard interdiction use (including targets within vehicles).
What was missing in essence was a section weapon which sort of plugged the middle, so a weapon that covered 800m to say 1200m and was also a section or platoon weapon. The Afghan war and the war in Iraq highlighted that specific need.
What has happened is that the US Marines have now adopted (for trials at least), you've guessed it, the 6.5 CM as that intermediate range sniper calibre, and bought a shed load of new rifles up to train troops on.
It's highly likely that the UK armed forces, at some point, will follow suit and adopt at least a platoon level, if not section level intermediate range sniper rifle. The 6.5 fits that bill perfectly as do a number of 7mm options (I'm surprised actually that the 7mm options were discounted by the US Marines).