It sounds like a boring market to revolutionize but I would welcome Apple turning banking on its head. I would be happy to deposit my money in an Apple managed account and make purchases in the real world with my iWatch and iPhone. and online on my iPad and iMac. Just in case, I'd keep cash reserves in a safe. Despite all that Apple has done, the most world changing disruption would be if Apple took on the dominance of big banks.
It's a complementary service to the hardware. iCloud is boring but became a good selling point.