The last of the non-FN parts needed to make a non-FN SCAR are being developed by the private sector. Until then, FN will not likely sell parts, as they do not want to lose the substantial profit these rifles carry - think about it, the entire extruded upper and injection molded lower design was made to save money versus an AR that starts with a forging that needs a bunch of follow-up machining. And yet, you can build an AR for under $500 .... so the $2,000 plus SCAR design has a HUGE profit margin.
By limiting parts sales, people can not easily build using 90% of the after market parts available, and buying the last 10% from FN. As soon as those last 10% parts are available, FN has to drop their price.
Lowers are available, uppers are available, triggers, barrels, I know someone working on end plates. I think bolts and bolt carriers are some of the last, and people are working on those. Generic brand SCARs are coming.
. I thought the 1950's were over and I think I said battle rifle. Oh, you forgot about the M1903? 
