I dont know for sure, but I think banks can end Bitcoin. And if you ask me how they are going to do that, I think its by protesting with claims that Bitcoin is ruining everything they have ever worked on, then you will see the government interfering in the matter.
And when government decides to stop, they can do that at once. The only reason why Bitcoin is still being used is because there are countries where it is being allowed. So dont say that banks are afraid of Bitcoin, they are not.