I think there has to be a way to create a tracking system for bitcoin. Every wallet must contain ids. Otherwise, bitcoin can be always used for money laundering. If you want to launder money, you can find a cash seller everywhere. After bitcoin is bought, noone can prove whose bitcoin it is. I think this is the only think that preventing bitcoin to become a global currency. Do you think it would worth this much if it is trackable. I dont think so. There will be altcoins that work with tracking system and ids. They will become a global currency. Bitcoin? I think never. What do you think?
Tracking every Bitcoin maybe impossible, for now. Tracking can even be invading the privacy of those who are doing Bitcoin-based transactions. There are effective ways that can minimize the incidence of money laundering like cryptocurrency exchanges requiring their users to do the KYC requirement. And even if all people will be doing the KYC there is no guarantee that Bitcoin can be a global currency so why waste time and effort? There are other factors why Bitcoin is not yet a global currency and we should not be in a hurry actually...there is no deadline set for Bitcoin, right?