You are correct. There are other calibers/rounds that are definitely capable and available to civilians. I think it will be a long time until ammunition/weapon systems are available to civilian side in this caliber. If this is gonna be the future army standard issue weapon, then I am guessing the ammunition contracts are gonna be in the millions for just the initial delivery contract for ammo. There won’t be much available on the civilian side for a while. And I don’t think it will catch on mainstream on the civilian side until there is at least a few years of successful full scale implementation on the military side.
Add in that if the price remains as is, not many will be willing to spend $8K on this rifle and cost of ammo.
I predict like the SCAR, this rifle will be a flop. I expect it to be on the surplus market after a few years for much cheaper. Except the SCAR didn't get as huge of a contract as SIG. Which is why they're not on the surplus market.
The last gun that was, was the Colt M45A1. Which was offered to Gun Broker top members for like $1K a few years ago. The Marines MEU/Recon are switching to the M17/18 (SIG P320). Not all have converted yet, there are still units using the M45A1. Most recent pics with a date on them are the A-stan withdrawal jack up. The fallen Marines castkets in the plane are being stood next to MEU members with M45's.