Looking over the last five years, the 6.8 is a huge success. It's the #1 alternative caliber for the AR15.
It takes millions of rounds a year to achieve cheap plinker status, those who look to any non military caliber for that - other than .22 - are being intensely naive or worse. But, then again, some people thought Bushmaster or FN would get them new designs for the price of the 45 year old AR.
The 6.8 is doing great with those who demand terminal results. It now has dozens of suppliers of barrels, uppers, ammo, and finished guns. All the Tier One makers offer it. Hunters buy it because it makes the AR "legal" to hunt. It offers enough power to take down game, with reputedly fewer losses than 5.56. Apparently, there aren't that many feral French hunting canines to be controlled, hogs and deer are more likely.
So far the only other competitor would be the newly released .300 BLK, a Whisper copy. It can use standard bolts and magazines, but there really isn't much savings, if any. It's promised to have cheap plinker ammo made for it, and the supersonic ballistics are promised to be just like the 7.62-39. Which makes it a .30-30, at best.
Talk about reinventing the wheel.
I don't expect 25c a round, it's not a military surplus caliber, either.