That definitely won't happen. If it happens to accidentally fit an AR, they will simply call it an AR magazine.2. Separately from #1, if it uses AR mags, they wi have to be pinned to 5 rounds. But if it uses proprietary mags (think LAR pistol) then the possibility of having Troy Pump Action Rifle 30-rounders that just so happen to fit my AR and are legal is huge.
However; If they make the gun with a proprietary magazine (that won't fit anything else) then we will have the luxury of unpinned magazines for it.