Let`s us say that a exchange got hacked, Would there be anyway to ban those bitcoins? like blacklist the stolen coins so they cannot be used on the network? I know about going back in time with consensus of the network to a earlier block or forking and using that new chain, but could you just not ban the stolen coins? I mean make a way to do that?
You can monitor the portfolio and consequently monitor the BTCs. I can only see this way of having the assurance that you will know which BTC is stolen or not. But if the robbery does not know the wallet, I can not imagine how to monitor