At a certain point, Apple is going to run out of partners to piss off.

They have over $100 billion in the bank. With that amount of money, there will always be someone willing to partner up with Apple.

There have also been reports that Apple offered to purchase exclusive access to some of TSMC's foundry capacity in order to diversify away from Samsung for processor fabrication, but TSMC prefer to keep their options open. Apple's problem is that only Samsung operates at sufficient scale to be able to guarantee delivery in the volumes Apple needs.

Speculative at best. High density display sales are ever-increasing across the market - it makes sense for Apple to diversify the supply chain. That said, it makes little to no sense to feed your competition purely from a business standpoint. Samsung can of course continue to sell their parts to other OEMs.