I suspect if Apple really wanted to they would probably start to produce their products in two lines like Nvidia did, with cheaper phones produced on something like Samsungs 4nm and the higher end phones on TSMCS 3nm.

This has the added benefit of diversifying their supply chain (to a degree), giving TSMC less leverage over Apple and potentially reducing the production cost of the lower end phones.

Wouldn't be the first time Apple has used multiple vendors for their SOC. The 6s for example had SOCs made by both Samsung (14nm) and TMSC (16nm).

No, but they can use their massive war chest and expertise to ramp up a competitor or become one themselves over the next decade or two. With massive corporate ships like TSMC and Apple it takes a long time to change course but they work on longer timelines so a big negative shift over a long time scale is an alarming signal.

Remember when there was no way that Apple would ever be able to move away from Moto?

Remember when there was no way that Apple would ever be able to move away from IBM/Power?

Remember when there was no way that Apple would ever be able to move away from Intel?

If you think Apple can just buy their way into fab success, you don't understand the complexities of semiconductor manufacturing.

No one is saying they can "just" buy their way into fab success. However, I think they do have the cash and clout to make it happen on a decade long timeline, possibly in league with Intel/Samsung or the US Government, or all three, etc. Obviously that would be enormously costly and risky, but any move to eventually do so is a threat to TSMC, so even if they don't do it they have a negotiating position with TSMC right now because the relationship is enormously valuable.

Eh. Might know a thing or two, but I'm sure you know what you're talking about.

Have a great day!

Sure, but how are they going to produce iPads and iPhones before then? They can't have more than a year's worth of CPUs stockpiled.

From TSMC chips. Basically if TSMC insists on raising prices to levels above what Apple is prepared to pay they can threaten to move away from TSMC eventually. If TSMC refuses to budge then Apple will have to pay the higher prices in the short to medium term and then expend capital to not be beholden to TSMC over the long term. So then the question is does TSMC value the relationship over the long term or do they value the higher prices in the short to medium term? That could be Apple's negotiating position.

Apple could with some pain replace TSMC but TSMC can't really replace Apple. While Apple is a demanding partner they pay their bills on time and can and do front R&D money. Once Apple's deliveries are made TSMC now has a money printer on the new process node Apple paid for.

I wonder how they would react if they were offered 25% of Apple's 3nm capacity at the higher price.

This could be a good lesson for everybody.

Sounds like they're playing a game of chicken.