I think bitcoin will not reduce corruption. As long as there are people who can be corrupted, it does not matter what the currency will be.
Bitcoin as a tool can be used for corruption suppression, because bitcoin can be transparent. It's very simple, if some government sector have a wallet and funds that needs to be used for something good, everyone can control them, they will not be able to use that funds for what they wish and how they wish. That will be a huge change, in my country its hard to get some documents about government spending, but with help of bitcoin and blockchain we will be able to check them from home in any given moment.
Now, and before, government officials are spending tax money for their own interest, when will that stop? In my country all politicians in power are getting rich while they are there, when their mandate ends they have a lot of money and then they are starting with other businesses, of course with stolen money from tax payer's.
FOR HOW LONG, I'm asking you? For how long they will be able to do it? As long as we let them...