Agreed, the writer missed an important point, it's a 40% savings in ammo weight. They are making a bit of noise about it, what will happen in the real world is the soldier will carry 40% more of it.
The issue of the soldier's load was addressed a long time ago - and the problem isn't getting better. The American soldier in combat carries double what his opponent does, add body armor, electronics gear etc, and we are approaching the need to have an exoskeleton to hump all the gear.
What we do for the MOST effective soldiers is train them more, strip the gear, and then send them into combat without it. Those guys are typically in special units and behind the lines. The rest are usually stationed in Green Zones and they sally forth on patrols. Not the average duty someone with a bedroll and semi auto rifle was doing living in a foxhole during the Battle of the Bulge. That warfare is rare, now. Much more of our fighting is in urban built up zones where it's door to door and more ammo is becoming critical. Urban combat requires a much higher expenditure of rounds (and grenades, etc.) to breach buildings to clear them, and body armor is much more necessary to protect the highly skilled soldier we can't replace overnight.
They can and will. Different rules for each side.
In the big picture sweeping up plastic cases to send to be recycled is an internal logistics victory for us. We go to huge efforts to police up brass, turn it in to be counted to prevent theft, and the sell it as scrap to recover the costs. It's also an incremental tactical issue, brass underfoot or being ejected to bang off the surroundings adds to the revealing a location. With a suppressor in use it adds to the noise signal, and bright brass getting ejected adds to the visual signal. No brass does aid the soldier, it's a little thing but it adds up.
For the weapon it requires some other method of sealing the chamber, brass expands and cuts off gas well. Once the brass contracts back to normal, however, it's helping push the now unlocked bolt open. Because of the way the new chambers have to seal without brass and the relatively softer material, the polymer cases are best pushed forward by the new round to eject. This isn't bad as there isn't an old case to jam in the feed system being extracted and ejected thru the action, it's a linear flow. It does mean that the shuttling chamber has to be larger - but that aids in heat management and also air flow as it's separate from the barrel - which heats up about 6 inches or more down the rifling far more where the flame front is pushed. Colt once had an M4 test video where they pushed the weapon with continuous firing and the first thing to overheat was the gas tube, then directly under it about 6" forward setting the handguards on fire. Cookoffs with an attached chamber are a known subject but it's the barrel warming back to the larger mass, not the chamber forward. Barrels droop forward when overheated, which is exactly what happened in the Colt video when a bullet perforates the barrel.
While there are advantages to the separate chamber it does add to the complication and weight, and the propensity to be piston driven adds it's increment. Add larger diameter bullet, the cased round is larger and heavier, which then diminishes the amount of ammo carried. There are concerns it would be an even tradeoff to go LSAT with all that.
I don't see the soldier getting much benefit from it all looking the big picture, perhaps a few hours less on a range fire policing brass vs a final loadout weight in the field just as bad as before. That big picture view is actually the more common problem discussed in posts on military oriented forums and blogs. LSAT is great in the narrow focus of cartridge weight, add in the more complex rifle, then the soldiers loadout, and last but actually more important, the changes in the overall logistics, and we are entertaining a small improvement at best, for a lot of money.
As for reloading look to what has happened in the black powder hunting rifle, it's all about sabot rounds and pressed pills loaded simultaneously. Not much different from the LSAT in terms of components. We are already seeing the tech being used.