I think blockchain is a new form of bank in the future, so the possibility of fiat banks will not follow the path of bitcoin because banks are looking to profit from deposited customers' money.
Yes, corruption not only shows up in the goverments, it shows up in the banks also , so blockchain system will help the banks to spot the fake and corruptions in the system.
Corruption will not be possible without the cooperation of banks, in my country is very common to hear news of politicians with secret bank account in other countries, but how is this possible? The banks should do a KYC and ask where that money came from but they do not since they know they get better benefits helping those politicians than if they exposed them.