For me the use of dark bitcoin will continue but not increase significantly. there are many coins that focus on the privacy they can use. Some instrumental time in the hands of thieves who always manipulate the system to be able to support them have a bad purpose like personal criminals, even on bitcoin technology is very difficult for everyone to be able to manipulate it because it's high security software that always makes it almost impossible to be manipulated and if anything happens then most come through the account holder later on.