If everyone stopped using them eventually the big companies would get the message.
No, they won't. And some people like the self-serve. I generally do. It's quick and easy and I don't need to talk to anyone.
I've done business cases for banks looking at how to reduce their fixed costs - branches cost a huge amount of money to run, but if their advisors are occupied doing menial admin tasks then they aren't getting in enough money and aren't actually adding value to the customer.
If I need to get money out or pay money in, then I can do it myself, no added value from someone doing it for me. Same with a transfert - I can do it online, whenever I want, and there is no added value to an advisor doing it for me.
What is added value is decent advice, e.g. sorting out a mortgage. That is what advisors should be focusing on.
In the end, the banks have generally decided (in France) not to close down branches because they are useful for advertising and being an entry point for customers ("pavement presence"). However, the use of branches has been dramatically declining over the last 10 years so it's totally reasonable for banks to look at closing/merging them.