Without central banks, bitcoins won't exist. They are both in a different class of their own. None have to replace the other. Why should they? Irrespective of what we thing of the government and global financial institutions. I don't mean to sound pessimistic but if bitcoin "kills" central banks the world would experience chaos like never before besides I believe this was never the intention by Satoshi when he/they created bitcoin. We really have to chill and stop sounding like the group on Reddit Forum that want to see bitcoin die.