First and foremost, blockchain technology will be the new system that will be running the financial ecosystem.
What is the backing behind this claim? There is no such thing happening thoroughly in the system. Maybe development is occurring in the IT firms but how much is still unknown. But claiming so without any backing is a wrong thing to do.
And moreover, the decentralized nature of blockchain technology do not really need a body or institution to be in charge of how transactions are made.
It depends whether they want to have a control or not.
Everyone will be in charge of the financial activities in the financial ecosystem if bitcoin and blockchain technology take over the financial space.
Very easy to say once again but without any proof to back your claim. While it would be bullish on the market and a good way to proceed but this is only speculation for now. Do provide some unbiased sources on how you are coming to this conclusion.
They do not know the transaction it will be very difficult to trace it.
It is not really that difficult as we think it is. Bitcoin is pseudo-anonymous - using a good blockchain forensic service this can be traced back to a very likely wallet. Then KYC the wallet user for an exchange and you have their data.
People will even escape from paying tax.
They would not escape taxation again like what I said above. If bitcoin would become global the banking system is way more cunning enough to be the first proponents of who are going to take the power away from the users decisively before they even notice it by putting in hardcore KYC systems on every exchange.