http://www.thetruthaboutguns.com/2014/01/foghorn/new-fnh-usa-fn-15-modern-sporting-rifles/
One caveat is that they won't be making them on the same line or with the same machines, in order to prevent full auto parts or guns getting mixed up.
No reason to think Colt is doing that, either. The lower is a different CNC program, and nobody wants full auto trigger parts to go out the door in a civilian gun.
But, you can't install them anyway, it takes another pin for them, so the concern is a bit overstated. We get to use full auto carriers and full auto hammers anyway. If anything, Colt bent over backwards with their semi auto parts, even going so far as using two different sized takedown pins, which the ATF seemingly cares less about.
All in all, another milspec maker offering a near issue firearm, and likely just as good if not better than the 6920. What's not to like, FN has been making military issue rifles for quite a while. My issue rifle in the '90s was a FN. Other than the rollmark, I saw nothing different than the others. The A-series was more important than the makers.
Until we get thousands of them in the hands of shooters who stress them, there won't be anything really known, and likely it will just add to the marketplace with another well made carbine.
What will be fun is reading the future threads titled "FN-15 or 6920?" There will be a lot of talk not backed up with facts, and then the truth will come out about what parts are supplied in common, what one makes vs the other, etc.
Then the "milspec" contestants will line up justifying one complies more, as if we need that minimum standard. We can do better.
More fodder for the forums.
Good luck with your endeavor, we need someone to "beta" test them.