Proliferation of HK416/417 in the GAF is increasing (actual designations are G27 for HK417 and G38 for HK416), the Dutch use them in many areas, the French actually made an official move for their entire forces. So thats actually not so far off, actually most SOF already use them in aforementioned countries.
I think there's a great case for the 416 by all of those countries. No doubt about it. It's a superb rifle that's on a seemingly perpetual winning streak.
The part of their decision process I can't see is the British saying "
Bobs yer uncle...., it's of huge importance that we use the exact same rifle the Germans use."
And the French saying: "
sacre bleu - It makes no sense for us to be using a different rifle than the Dutch."
Sharing calibers, magazines - yes, totally. Same specific make/model of rifle between

different countries with vastly different sized forces and economies, spanning an entire continent? I just can't go that far.