The sense I get from John Farnam's mailings, which probably draw mainly on USMC sources for military items and may extrapolate a bit broadly at times, is that the 6.9mm SPC is dead in the water as a military round.
Sources I had over yonder mentioned some time back noted that the 77 gr SMK 5.56 mm ammo (whatever the military coding) produced much better resistance to wind drift and satisfactory results without the need to change anything but the ammo. It is interesting that Remington has introduced a .30 AR compatable round commercially.
On a related note, the FN USA website notes that while the SCAR-L was approved for purchase, reality is that the money will be spent elsewhere.
Thereby freeing resources for additional study on what the ideal next combat rifle will be. Expect scads of computer assisted "enchancements" to the weapons systems capabilities, undoubtably at the expense of usability/reliability in the real world.