My fear is that it, too, will be decided by the courts, and that the ruling will be favorable but will come over a year after the ATF's arbitrary deadline that makes many of those still in possession of a brace a felon.
Meanwhile, my friend has decided his brace simply won't gracefully come off his purchased-as-configured AR pistol, and the only recourse is either NFA registration or cutting the brace off the buffer tube. Brace is securely glued on there, which may end up meaning destruction of the buffer tube itself. What's next, ATF? Ya gonna try to illegally legislate that pinned and staked flash hiders no longer count toward minimum barrel length?