All true. Then again keep in mind that the US army has tried to replace it's trusty warhorse several times: ACR -program late eighties...
Is a rifle that is 10% better reason enough to invest billions of dollars into it? On the other hand, the update has to happen at some point and current world events might give it the boost it needs.
Let us not forget that ACR was leaning heavily towards the “HK ACR” coming out on top ... when the programme got canned in 1990, as an early victim of the infamous “peace dividend”.
By all appearances, what happened was that Colt had got wind that their candidate was going to be dropped from the programme and therefore put their famously influential lobby on convincing Pentagon that hey, the Russkis are pulling out of the arms race, so why invest all these billions in a weapon nobody needs — after all, none of the candidates is all that much better than the (ahem, Colt) weapon we already have?
Interestingly, Colt didn't even submit a candidate to NGSW ... so as I said, we'll see where it ends. But a 10% (a bit more than that actually, but anyway) that makes the difference between a weapon that is effective on the battlefield and one that isn't might be worth some investment. Better pay the bill to SIG than to the butcher, right?
It is as you said: the change needs to happen — the M4 cuts no mustard outside GWOT, never did. The US is now in a crossroads between allowing its riflemen to remain a factor on the modern battlefield, or becoming obsolete.
The Finnish-Swedish co-op might happen indeed, then again the Finnish army just updated the RK62 to 3 different versions and the caliber is pretty good still against modern body armour ...
It bears noting that the 6B45 is rated as protecting against the Russians' own 7.62x39 AK rounds — i.e. the RK62's calibre — and 7.62x54mmR sniper rifle rounds. I believe the Finns recognise the need acutely enough ... and the Swedes, stuck with 5.56x45, even more so.
I have been able to fire the M3 and it is indeed an improvement but it is still the "same" gun.
That should mainly be because it IS the same gun, shouldn't it? I mean literally the same, physical weapons, just refurbished. And that was — what? three or four years ago? Times have moved on rapidly....