In theory it could make central banks dissapear. I think in the future regular fiat cash will eventually be replaced by digital cash.There's just too many advantages. I watched a documentary about counterfeit us bills the other day and there's billions of it being made and flooded into the market. The bills are so good that it's hard to tell them apart. Bitcoin solves this instantly. Bitcoin also solves the issue of banks being able to print it as they like which as we know devalues the currency whereas the opposite is true of bitcoin.
Bitcoin is a full currency i think , there is no real difference between Bitcoin and the other currencies nowadays, fiat is used more till now that's true
Bitcoin is a currency indeed, but it will be not possible that it can make the banks disappear you should know that there are a lot of people that is still using banks.
And they dont know even how it works and that is the problem you have to promote it more.