No it doesn't actually. The a banks electronic clearinghouse and transaction processing system can handle potentially billions of transaction per second. No cryptoshenanigans required aside from that required to secure data at rest.

You're making a claim that something predicated on everyone wasting tons of power to do hashing that just gets thrown away when the first person nails it and starts propagating, and all of that per 100 or so transactions, with at max maybe two to three dozen servers per bank, with full capability to reverse, adjust, reconcile, chargeback, so on, and so forth.

So no.

No, they won't shut down traditional financial processing. They don't need to.