I suppose the changes will be seen earlier, in the nearest 8-10 years. Today they have already started to talk about decentralized internet. Less people will start using banks, and banks will have to reduce their commissions.
Banks are just going to evolve and adapt to bitcoin, I'm sure they are thinking about it, if possible they are going to prefer bitcoin to be destroyed but if that is impossible they are going to try to become the winners in this new system, in fact I will not be surprised if banks have already began to buy bitcoin secretively at cheap prices the last time bitcoin crashed so it is possible they are in fact interested that bitcoin gets major adoption to make a lot of money.
Banks are unlikely to embrace Bitcoin or some other crypto any time soon. They are all heavily regulated, and it is impossible for them to start accepting cryptocoins entirely on their own. In short, it won't happen until central banks allow them to do that, but this is even less possible because crypto is a strong competitor to national fiat currencies. Only a few small countries have accepted a foreign currency as legal tender, but no country has so far accepted Bitcoin fully.