100% impossible because bitcoin is not accepted by all countries and there are many country which are against bitcoin. and bitcoin is not the safest form of money because it has limit of 21 million so this would definitely cause crisis.
Exactly, the reason why it does not seem possible for bitcoin to make banks disappear is the limitation of it, because bitcoin has a limited amount while if it is accepted by even one country it may don't be able to cover the economy of it, so what if more than one countries accept bitcoin? There would probably be problems in this, only if the amount of bitcoin can be increased then maybe it can do something like that.