That is actually a good point - the fab process would turn out to become another weak point (besides the missing moat of ARM) of Intel. There is no way Apple would watch TSMCs leadership year after year and still stick with Intel fabs.
Apple hates being beholden to one company. It’s bitten them many times in the past.
I suspect if anyone else could keep up with TSMC Apple would still dual source.
But between their lead and the benefits of being such a big customer they get first crack at the cutting edge stuff, single sourcing manufacturing probably makes the most sense.
And their interests are aligned, unlike their dependencies on MS/Adobe/Motorola/IBM/Intel.
