Well, as I understand it the fountain of Scar had been cut off at the source. If they make a Scar 2.0( or 18s or whatever they'd call it, it would be deemed a variant of a prohib, and thus be prohib itself.
From what little I know, this is why we're not swimming in NR black rifles. Otherwise someone could just make an AR16 or a million other flavors, and subject the verification lab to a Chinese produced gun based DDoS attack until one slipped through.
A new design for the market needs to be just that, a new design. It's part of why things like an XCR are priced alongside top tier ARs, rather than costing $1000 like comparable guns, because they have no real competition and they cost so damn much to make. A big part of designing a new gun is finding all the necessary wheelbarrows to transport how much money it's going to cost you. Last I checked it's up at around a half a million dollars for many projects I've heard of. With the looming spectre of prohibition, not many people have that kind of cash to burn.
This particular method of prohibition has murdered an entire branch of our national industry. There are very few truly unique designs in life or art, when they come around they are precious and fragile and generally get squashed by industry giants. By restricting something as iconic as the AR15, they have neatly crippled entire generations of future designs, because now people have to go back and work with hundred year old designs, that may or may not have been prohibited or restricted themselves. Or create something entirely new that somehow escapes being classified as a variant of any number of scary guns that came before it.
However, the SAPR has not yet been gutted, there is some faint hope that if we rub our hands together for long enough the verification lab will get good feelings and push it through. Or we'll all die of old age, and one of the new guys will find it at the back of a shelf and ask what it is, and the last remaining old timer will have forgotten and they just approve it to get rid of it.