The only charitable part of this idea is that it will insulate the stock price from the actual balance sheet. It asks investors not if they want to invest in an EV automaker but in "Elon Musk Inc" essentially. He's been doing some variation of this his whole career, this would just give him the ability to dilute the numbers of each component industry further. The problem is the brand name of Elon Musk is worth a lot less than it was in the 10s.

A payments platform is not a bank. Beyond the services being different and the customers being different (consumers vs businesses), both had to partner with... well a bank, to provide the actual financial services.