Also: Before, Apple was dependent on Intel (whose "product" is an integrated chip design and the fab to make it). Now they're dependent on TSMC (whose "product" is a fab). I'm... not really sure they've reduced their dependence? If TSMC starts falling behind Intel--which doesn't seem likely, but what happened to Intel didn't seem likely two decades ago--Apple will be stuck.
TSMC does have competitors.
Intel is already being evaluated to fab Apple's entry level chips, if they can meet performance, energy efficiency, and production targets.