Banks are what we call one of the pillars of a country. So if we removed them, that country will be crippled so it doesn't makes sense at all to opposed or even think that they can be replace by crypto as a whole.
I don't know how the crypto could stand on its own though, did the OP mean self-regulation? or some authority overlooking everything? Crypto is decentralized so I don't think it will stand on its own, in my opinion. Plus the price keeps fluctuating and chancing by the minute how can it stand when there's so much outside factors that really affects it?
Also, it is already obvious that cryptocurrency will not be standing on its own while looking at the angle the government are going with regulation.
Banks are already established from generation to generation and no government will be giving that up for anything, and at the same time, cryptocurrency may get established more like we have always had the stock market but in a different form with the government still in control, one way or the other.