6.5 Creedmoor is a better mousetrap for 7.62 NATO sized guns but that does not make it an intermediate cartridge. DHS is only going to it for precision rifles currently in 7.62x51. AFAIK SOCOM is doing the same.
Those propriety AMU cartridges are being developed as an intermediate cartridge / 5.56 replacement, not a 7.62 med MG cartridge replacement. Apples to Oranges.