Branches mean large overhead costs. Think high street retailers vs. Amazon. More than 600 bank branches have closed across Britain over the past year and about 3,000 over the last decade, leaving around 8,000 now.
Here’s an extract from a PwC white paper entitled Retail Banking 2020 – Evolution or Revolution:
Every bank will be a direct bank; branch banking will be undergoing a significant transformation. As technology enables every aspect of banking to go online, and as cash usage falls away, traditional branches are no longer necessary. Given their high-fixed cost, branches will need to become dramatically more productive, or significantly less costly. Banks have already reduced staff levels, closed the most uneconomic branches and started experimenting with new branch concepts.
We expect these trends to accelerate, as customer expectations and behaviours evolve. Branches will remain, but take many forms, from flagship information, advisory and engagement hubs (offering education, financial advice, full-service capabilities and community offerings) to smart kiosks (offering service, sales, cash and video contact with a range of specialists). Leaders will rapidly improve their footprints, reducing branch size and costs, introducing new models and migrating transactions to low-touch digital channels. Digital capabilities will improve, so that branch service officers and bank customers use the same platforms, with the same look and feel. The human touch will always be available, just much more through digital channels. Banks that are behind this trend will start to struggle, due to structurally uncompetitive economics.
“The human touch will always be available, just much more through digital channels” is a key point to consider. If cash transactions are falling away, face to face video support becomes available and identity verification / identity document verification is automated, are branches really necessary?
There might be a clue here: 
Btw, I meant to post this last week about customer support through video: