Mixers are otherwise perfectly legal (which was acknowledged by a
blog of McAfee, a firm instrumental in the takedown) and I don't see that changing in the near future. Lawmakers don't ever talk about mixers and I would be surprised if majority of them knew mixers even existed. I could see mixers getting on their crosshairs if a single provider gets big and popular enough, but the service itself is so niche that even the most well known ones remain obscure to the general public.
Senators Feinstein and Grassley have tried twice (with some co-sponsor support)
to re-define mixers as financial institutions. That would subject mixers to banking regulations, as ridiculous as that sounds. Nobody cared enough about cryptocurrency during the last couple legislative sessions for the bill to move forward, but that's probably changing. The FATF is just a veil for the US government, so we'll probably see a similar bill pushed by some very powerful people over the next year.