You gotta be kidding. There are probably close to 100 companies out there making ARs these days. You need a list? Rock River, Smith and Wesson, Colt, Noveske, Model1, Stag, Oly, LMT, Wilson, Barrett, Fulton, Armalite, CMMG, Charles Daly, Del Ton, Cavalry, Clark, Double Star, Baer, POF, Sabre Defense, Vector, Yankee Hill.
That's just the list off the top of my head without any coffee.
Cereberus owns 2 of them (Remington doesn't really count, its just a rebadged rifle). Again, the numbers just don't add up to what you are saying.
Closing Bushmaster and DPMS would simply move the market to the others.
Cereberus is not in a position financially to buy all of them, nor can they.
Guys like Ronnie Barrett are not likely to sell out, there are others.
And since the AR platform is basically open source there are no copyright issues if every guy with a machine shop decides to enter the AR business.
Cereberus doing what you describe would be an annoyance in the marketplace, at worst, and make some other very pro gun companies a lot of money.