Whatever that caused bitmixer to close(I forgot what caused them to close), might can also be the cause ChipMixer to close in the future if it was something involving the government or something.
Nobody knows what caused them do close. There is only speculation for example here:
https://bitcointalk.org/index.php?topic=2194145.20Thanks chipmixer for posting my thread's link here.
Man as they claim they closed it because they think bitcoin won't be used for drugs and etc.. In reality it's not reason and I hope people realize it. They wouldn't say that they are afraid because of alphabay was seized and their mixer was used to send coins here. I believe they lied reason and I believe they shut down their website to avoid being in jail and I appreciate such smart way (some people are so numb, they would continue service to get much and much money). Also bitmixer was pure profit machine, they had huge profit, it was millions in year.
Reason of bitmixer's close was seize of known drug markets, that's all, they were source of their money and if they would continue service, they would be seized also.