Yes, the caliber is definitely becoming established beyond the AR-15 market. Ruger also offers the caliber in a bolt-action rifle with threaded muzzle - very interesting. Another new offering - the company that is building the StG-44 semi-auto replicas has caliber options of the original 8mm Kurz, 5.56 NATO and 300BLK.
I had to look that up. Looks like HMG is offering conversion kits too, to swap between all of the offered calibers. Not bad.