Banks do not innovate at a pace that is noticeable.  They experiment with lots of technology but generally are laggers not leaders.  Since this area might be perceived as a threat or an opportunity to cut cost it is getting some early exploration but as such the industry takes a very long time to adopt anything new and blockchain will be no different.

Contrary to maximalist sentiment back then, I said in 2014 that mainstream adoption of blockchain was 10 years away, and I stand by it.