I'd have to go back and read the new bump-stock rule again, but I seem to remember it being worded so that it doesn't apply to binary triggers as-is. I could be mis-remembering though, it's been a long time now.
Of course the reality is that the ATF can come out with opinion that could ban almost anything. If a binary gets used in a crime, and the media figures out that it was, I'm sure the ATF will change their opinion on them as well. Or a 'brace' attached to a pistol.
The last wording I saw was “Rate of fire increasing devices.”