Mixer is a tool to make you stay anonymous, so assuming you did right and know what you're doing, how can someone able to know your location and knocking your door? you must be leave your identity somewhere and it's already kill the purpose of mixer.
There is a good
thread about how it is not that difficult to break mixers in the sense that whoever has the knowledge, resources and time can connect the dots and come to the conclusion where something came from and where it went. Those who analyze blockchain today are already so successful in this that even mixers do not pose too much of a challenge. Anonymity online is something that is talked about a lot, but being completely anonymous online is a big illusion.
Using mixer will be expensive because the current regulations is full of KYC, so it's not gonna be easy to stay anonymous.
I don't think that using a mixer will be any more expensive than it is today, because they will continue to try to be competitive and attract as many clients as possible. The fact that they will no longer be present on this forum does not change too much their way of doing business.