CUPERTINO, June 8 -- There are keynotes, and then there are reckonings. Monday's WWDC 2026 opening at Apple Park is both.

Tim Cook will take the stage for the last time as chief executive of Apple Inc. He announced in April that he will hand the job to John Ternus - the company's head of hardware engineering - on September 1. Whatever Cook unveils at 10 a.m. Pacific Time on June 8 will be the last major product narrative he controls. And the product that matters most is one he promised two years ago, failed to ship, and is now promising again: an AI-powered Siri, rebuilt from the ground up, running on Google's Gemini models under a deal that is costing Apple roughly $1 billion a year.

That is the math that neither the keynote script nor...