Apple has a whole crew of finance asset managers, investment pros, and tax attorneys managing its own cash hoard. It should just separate an arm of that group and create its own public facing bank to service customer financing / loans / credit cards.
The automakers have done it (ie: GMAC - which GM spun of some years ago into Ally Bank / Ford Credit / Toyota Financial Services [which I used to work for in the marketing staff] as well as Toyota's dealer focused bank used to help dealer's manage their wealth and their real estate investment assets / etc.).
Not hard to do.... cuts out the private label 3rd party... makes responsiveness to customer needs or market dynamics or new product launches with new offers for millions of global customers a speedier thing to accommodate when you manage everything in-house. And Apple loves to have vertical ownership of all processes as it relates to product dev and engineering. So they should apply the same logic to banking / credit / finance.
Of course, they want to use another bank's assets to facilitate the loans rather than tie up their own money with customers who may or may not be good risk. But risk assessments and FICOs in the approval process IDs the riskier paper and shunts those out of the pipeline. Again, if the auto companies can do it - and they are technology holdovers from the 1900s yet they make it work - certainly the most valuable tech company can do so as well. Right? Could turn out that an Apple Bank becomes more profitable than Goldman if it offers a large suite of services beyond credit cards and product financing. Possibly.