Blockchain sucks as a technology. Any instance where you have...

Blockchain sucks as a technology. Any instance where you have blockchain, especially for a centralised entity like a bank you described. You can switch out blockchain with something else, like an insert only database. I design and work with systems that involve these kinds of architectures as part of my work. Blockchain has never been a thought as a more efficient or effective means of a system design in any financial system I've worked with/designed.

Consider an exit strategy because this stuff is a load of crap.