Banks have existed unchallenged for hundreds of years, and that is the key issue here; Bitcoin, backed by a solid platform such as Blockchain technology, is a ghost that is incredibly hard to control due to its decentralized nature.
The power and control of money is being ripped away from traditional institutions, which can also be seen on Wall Street. Some of these traditional investors are siding with what could be the future, while others vehemently denounce it.
Individuals can now enter into direct peer-to-peer trusted exchanges with strangers. They no longer need a central institution to vouch for the other party.
Bitcoin is not a challenge to banking, blockchain is open source and free to use if they wish and some do to a minor extent. The International monetary fund says it may well employ a blockchain in future for some kind of digital money, I dont think they speak falsely as I've heard from a dozen or more sources that blockchain as a technology is respected.
They do not respect bitcoin as a source of value though because it is not unique in their eyes or patented even or with any military or national power backing it. Banks probably do oppose decentralised systems and peer to peer but I still do not see banks replaced by bitcoin, not all value they carry is false and not all of it is leveraged.
Even in bitcoin we find there are central points of value and a need for capital to provide investment. It can be crowd sourced but also the old idea of large funds and companies is not suddenly over. Banks will still exist within a bitcoin system Im fairly sure.
I disagree banks have been unchallenged. Banks have gone bankrupt and had fascist and communist governments in control, as an idea they still carry on now. Largely a bank just exists to mediate between borrowers and lenders, we'll always get some leverage on demand for business from other business I think. The competetion I see from banks to crypto is their mobile apps, I worry these will be more usable to the common consumer then anything crypto gives bar the price gains