Bitcoin mixers have a long history since they came into inception some time ago. They've been a viable alternative for people looking towards privacy within their Bitcoin transactions. While Bitcoin mixers are far from being perfect, they're still one of the best solutions for obfuscating transactions from third parties. The only concern would be that mixing services are centralized as they're provided by a middleman. In effect, this brings a single point of failure greatly defeating the purpose of privacy.
We've seen how Bestmixer got shut down by the authorities. They claim that Bestmixer encouraged money laundering activities which resulted in legal action. The truth is that Bitcoin mixers can be used for both good and bad things. Money laundering is mostly done with Fiat than with cryptocurrencies like Bitcoin or Ethereum. Still though, the perception of worldwide governments against mixers/tumblers seems to be different nowadays. Which makes me wonder whenever Bitcoin mixers will be considered illegal by such entities within the future?
If governments ban mixers/tumblers, then they could easily do the same to privacy-oriented cryptocurrencies like Monero and Grin. It's all a matter of power and control over people than anything else. What do you think about this?

You have actually bring another angle of discussion to the mixing part of crypto hemisphere. Of course there will be series of opposition from the part of government if they realize that the services being provided is making it difficult for the tracking of people who engage in illegal activities. At the same time, it would be fool hardy to focus on the mixing services as a way of crime control rather than the exchange sites where controls should be established. When the exchange sites promoters are made to be responsible for the coins in their custody, they are expected to take it serious and ensure that maximum security is done to that effect.