They ought to simply accept the fact that the AK-47 is the perfect service rifle and adopt that. Why prolong the inevitable. The M-16 is a fragile piece of shit built so that when women are drafted as cannon fodder they can at least carry the thing in battle until they fall over from heat exhaustion and the men can trade it to the indigenous population for cigarettes and toilet paper. It's one advantage is it is accurate to about 500 meters.
I think the only reason for the change is to reallocate funds from one part of the military industrial complex to another part.