Anything to worry about if you use mixers and not doing anything illegal?
Will any one come knocking on your door if you use mixers and not doing anything illegal?
Will posts like this be banned too after Jan?
Will using mixers be an expensive?
As was pointed out, generic discussions of mixers would still be allowed, as long as nobody is mentioning specific websites or suggestions to find specific websites. I've never used Bitcoin mixers, and I'm not planning to use them in the future. As for what's illegal, it always depends on a country. You should check the legislation of the country where you live, as well as see if there were any notable cases of people getting in trouble just for using mixers (and not people getting in trouble because of using mixers to launder money, for example).