I dunno, Apple has always had a pretty high level of hardware independence, and one could imagine even if Intel did produce great chips for longer the ARM architecture would replace it eventually. Certainly the timeline got shifted (and I'm glad for it) but I don't know if that really impacted Siri. If anything it seems like it got pushed to the bottom of the pile in favor of projects like the Apple Car and Vision Pro OS one on side and the demand to increase services revenue on the other.

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.

A series is their own chip design, not Power PC or Intel designs.

It's the CPUs they have built for their purposes, which is next level hardware independence.