Cook was palatable to both Wall Street and Apple employees while SJ was on medical leave. IMO, he's passed the test already. Everyone was willing to accept him then, back when there was serious doubt about whether Jobs would return after his leave. So there's no reason why they wouldn't be willing to accept him in a genuine succession event.
Seems to me that the post doesn't fully address the most important fact: "He cannot be replaced..." Gruber takes the paragraph to points about what Jobs' absence will do to the stock, and then takes the rest of the post to talk about the sourcing of the story and who might eventually replace him, but those strike me as ancillary issues at best. Jobs can't really be replaced, can he? Certainly Apple will continue to m…
Jobs is a time teller. He can look up at the heavens, see the positioning of the stars in the industry and tell you exactly what the time is and for what. It's extremely rare for such time tellers to exist, and it's doubtful anyone exactly like Jobs will ever come along.
However, for any great company to stand the test of time it needs to answer the question who tells the time after the time-teller is gone? That's why a company built to last is like a clock. It is a part of the ethos and the system for it to tell the time, and that's the bit that makes all of the difference.
So, if he has spent the last decade making a clock, then Apple will survive him and the loss of Tim Cook, Ive, Schiller and almost anyone you think is crucial to Apple's success, because the ability to predict and act on those predictions would have been built into the structure of Apple itself.
I hope that made sense.