You notice the link just sez "6.8 round" and has no referance to SPC. All other sources that I have say this will never happen.
I basically say . . . Huh,What,Why ??? What does the Army need with .277" over .224" given the way that they use the gun(s). They should not be shooting 600+m across the desert anyway. Hell . . . call in an air strike.
The 5.56X45 is a great chambering. Instead of looking for new,how about just fixing the old. Come up with a heavier loading for the 5.56 (maybe a 75-77gr) and for the 7.62X51 a lighter load (maybe a 125-135gr ).
In my time in the military I have shot quite a bit of both chamberings and it has always worked for me (us). Both in extremely close combat and shooting out across the open areas.
Of course nowadays you still need to arm the shooter with training and expierance. Unfortunately this is sadly lacking in most units.
My prediction is - - -> The 6.8 chambering will never come to pass. --- SAWMAN