The LSAT is moving along to the Battalion level tests, with hundreds of prototype rifles, and SOCOM has signed on as a development partner. Read into that whatever you want, especially in light of them dumping the SCAR.
Caseless really isn't what is moving forward. The LSAT is a polymer cased round, with the propellant telescoped around the projectile. There's video out there demonstrating a belt fed LSAT firing off 100 rounds with no difficulty - which should be more concrete information about "carrying off the heat." Brass cases didn't do that much, another video of an M4 being fired to destruction is evidence the barrel is largely responsible for the job. Most MG's are NOT operated continuously, they simply cannot handle the heat load. That's why so many were water-cooled for static defense, and why the Army teaches "fire a burst of eight." Those of us who've trained know better.
What the LSAT does is reduce the weight 40% because you don't have to use a heavy brass cartridge to seal the chamber. With a side charging shuttle bolt, the mechanism seals the chamber itself, allowing the plastic case to keep the ammo clean, hold a primer, and contain the powder without chipping off particles and messing up ballistics. It shoots consistently that way, you can trust the trajectory, and get the same amount of gas pressure to operate the gun. Caseless couldn't do that with an exposed propellant.
The real problem isn't perfecting a design - it's getting the ammo industry to step up to production challenges. On one hand, having to acquire and capitalize new machinery to load the stuff means inventing it first. And without a million round contract, nobody is going to bother. Without big lots of ammo, the project gets stymied. There's also all the other stuff on the table: caliber? Ballistic range? Combat effectiveness, does it get more first round hits, or more hits at all? Cost savings not messing with brass cases, collection, salvage, transportation, etc? Big pluses there, but that has nothing to do with combat effectiveness.
If large unit testing shows it's easier to get more hits, then it's going forward. Each soldier carrying 40% more ammo, with a larger percentage of hits, means more combat firepower and superior control of the battleground. He can outhit and out fight his adversaries' larger numerical forces. It adds that multiplier to the defense even more.
Just because "caseless" hasn't quite made it to prime time doesn't mean it won't work. DI was around since the 1900's, it wasn't implemented for 50 years. It took the right engineer and application to get it adopted, and it's happening now just like Armalite was busy in 1958. You just have to look and see it, nobody's going to spoon feed you the news.
Remington getting the M4 contract is just a closing chapter in the history of that platform.