Hopefully in the future there will be tools that can trace
Bitcoin originating from illegal activities, so when we buy Bitcoin, we can be sure that what we are buying is not tainted Bitcoin.
Well, If I'm not mistaken, in the future Bitcoin user's anonymity will gradually decrease once a tool to trace tainted Bitcoin is created, and that means every Bitcoin in circulation is being monitored.
I'm not sure about this, but as time passes by, more users are looking for solutions to minimize the criminal involvement of Bitcoin by sacrificing our privacy.