It's argued that something will need to be done because doing nothing risks "systemic failure," which is something so bad that the entire economy might fail unless something is done.
Is that the right question? What about asking instead, "How big is 'too big'?" Why do we need financial institutions so big that they might drag down the entire economy if they fail?
What's the "right size" for banks? Shouldn't they be only big enough to serve their local economy without risking the national economy if they fail? But what's a "local economy?"
Answering those questions isn't easy. It requires first understanding the boundaries of a "local economy." Do we really need "global" financial institutions? Don't banks have to be bigger than the neighborhood coffee shop in order to have the financial clout to make something happen? What is that "right size?"
Here's a video that uses some fancy algorithms to give you a peek at how to answer those questions. Enjoy.