The 5.56 is going to be the "next" caliber. As of now, there is no need, and no plan to replace it. 2nd, there are about 5 threads on this topic. There will be a replacement in the future, no time soon though.
I for one am in no hurry to see the M16/M4 replaced works just fine but there are plenty of upgrades that could be done instead of wasting more money on a new weapon, but that's just my opinion. PEO Soldier is still following the OICW line, with OICW 1 being the carbine in 5.56mm. The XM8 program is dead in the water, HK's design was dropped and last word was that they are allowing companies submit their designs, but this was a year ago. And now that this has been said there's going to be a swarm of replies with "the XM8 should replace the M4/M16.
" Of course far in the future, there may be a swing away from projectile weapons entirely. There are advances being made in Directed Energy Weapons (such as THELS), that could conceivably one day be made into individual weapon sized platforms. That is years away as for now they have just finally been able to fit a Directed Energy Weapon and its power source into a 747. Miniaturization is the key to making these type weapons available for individual soldiers and that technology is as I said still years if not centuries away.So we will just have to rely on old fashioned bullets a little longer. I've also seen a big push for non-lethal weapons for battlefield use.
I'm not talking about the 12gauge bean bag slug and such. There is research into sound and light wave directing and amplification just to mention a few. The correct problem is the ability to use these weapons at the current weapons ranges. Yeah I have seen a lot of shows on Discovery and History about the "Less than lethal" weaponry being developed.
I think most of it is being directed for use against civilians in civil disturbance type scenarios or apprehension of suspects with limited use for military. IMHO, I don't think less than lethal weapons would do much in the way of winning a war, unless you could incapacitate an entire Regiment or Brigade for a sustained length of time, thus allowing troops to move and secure the area and the incapacitated troops. Then of course, our troops would be overwhelmed by the sheer number of POW's. I've seen a few "demos" at military conferences of non lethal weapons.
Most are as you described, for civil applications. However, there are a couple of companies trying to sell energy/sound directed weapons. Their angle is similar to your assessment. They contend that a few of these weapons can immobilize large groups of soldiers (even entrenched) for a period of time to allow our guys to maneuver or overtake.
I too question the effectiveness of these weapons. The wounding theory was an excuse as to why we were fielding a caliber of rounds that lack "knock down" power. The Soviets didn't care too much about causalities and most fanatical factions don't either. So the wounding theory is very thin.
If you are going to shoot someone then they had better be dead when it's over.
Victor Epand is an expert consultant for http://www.WarGear.info/. WarGear.info carries the best selection of military clothing, war gear, and combat accessories on the market.