Valid point as a GF-tied AMD would not be in the same position as today.
That said, what are the other options if not TSMC? Besides Intel, Samsung is only other cutting-edge option. Intel's 7nm would be technically on par with TSMC's 5nm (marketing names aside). https://en.wikichip.org/wiki/7_nm_lithography_process
There is a chance, however unlikely, that TSMC's 3nm push will run into issues and be delayed. Would create an interesting scenario where Apple would pay Intel to fab their SOCs.
There were rumours going around about its demise a few years ago, but a fair bit of that was simply their failure to ship 10nm parts on schedule AFAIK. They're still doing some degree of third-party manufacturing, and I don't doubt once they reach a point of having the capacity for their first-party products on 10nm we might seem them expand.
However, the inevitable flip-side of this is unlike TSMC/SS where Apple can bid the highest for the early production of a new node, Intel are highly likely to keep the new node for themselves to start with.
Intel currently doesn't have enough capacity to make their own chips and are rumored to be outsourcing to Global Foundries as a result ( https://wccftech.com/rumor-intel-moving-select-cpus-to-globa... - huge grain of salt on this one ofc, but the supply constraints on Intel's fabs are well known - they mentioned it even at their earnings call) - why would they stop making their own products to make Apple's instead? Apple'd have to pay an absurd amount for that to make sense.
That said, what are the other options if not TSMC? Besides Intel, Samsung is only other cutting-edge option. Intel's 7nm would be technically on par with TSMC's 5nm (marketing names aside). https://en.wikichip.org/wiki/7_nm_lithography_process
There is a chance, however unlikely, that TSMC's 3nm push will run into issues and be delayed. Would create an interesting scenario where Apple would pay Intel to fab their SOCs.