As I understand it, here goes...feel free to critique if I'm way off in the boonies on this...

Generally, the direction we seem to be going is the direction Russia went about 20 years ago {except as with everything, we will do it better}.

Just as they kept 5.45x39, we'll keep 5.56x45, but....they re-adopted {is that the right word?} the 7.62x39 to be issued for various purposes/operations and similarly we have been heading the direction of adopting a somewhat heavier caliber for certain units/operations as well. In fact, various special forces have been using a variety of calibers on what used to be called "trials" bases for a long, long time.

Problem with our current issue is that the 5.56 SAW provides essentially not much greater advantage to a fire team than an extra coule/three M4's in that it is NOT really a sustained fire weapon and its cartridge does a poor job of handling "MG jobs" like wall breaching, vehicles, and penetration of "soft" obstacles like dirt, wooden barricades and...guess what...concrete and block houses which we seem to encounter fairly regularly these days...

I remember some really disheartening videos of operations in Iraq demonstrating the latter thing all too obviously as suppressive fire was laid down on typical home structures in Iraq and you could just see the little bullets putting a little divot in the building and nothing much more. Contrast with Ancient History and a simple German squad circa 1944 with a 1200 round/minute MG42 launching 198 grain bullets at about 1500 fps. Literally give time and a couple cold barrels, you can saw a house down. I've shot one of those things and it is a thing to behold...

Further, for us today, we only have one other standard option, the M240 which is really a big thing not conducive to typical small unit operations,. so something better than the M249 and not so...much...as the M240 is needed. Anyway, the 5.56 will be around for a long time, but so will some of these other developments, including no doubt soon, polymer case ammo which will suck for us handloaders who rely on mil technology to keep our hobby up...as if Uncle cares about me and my Dillon Progressive presses...