For standard treasury, I believe that becoming a bank is a logical step and one that I would welcome wholeheartedly. There are so many things about the current monoliths I deal with that I hate and I feel like it's entirely possible for almost anyone to deliver a better experience.
They're in a hard place right now though. I don't think ST has any revenues to speak of and they don't appear to have raised any money post-YC. This is a business I really want to succeed but it seems unlikely to do so without a major cash infusion. I really like zt but they're in a hard place with no shelter in sight.
To put this in perspective, you probably need about $50M to start a chartered bank and you probably need $20-30M to buy a distressed one. Those are not ridiculous numbers for the kinds of returns this could have, but a bank will never have 97% margins as a business and so I don't know if this is a venture backable business. Now, a fund with longer time horizons... That might be interesting.
Edit: For the sake of clarity, I want to be explicit when I say that I'm pulling for standard treasury. It's a hard business and I really want them to succeed because I think it would be a net-benefit to almost all of us.