One of the questions that lingers at the end of Walter Isaacson’s biography of Steve Jobs is who at Apple (AAPL) is going to make the thousands of product decisions — large and small — that used to be made by Jobs himself.

The issue is especially problematic because no one at Apple has the power or authority that its co-founder brought to the company, and because his hand-picked successor, CEO Tim Cook, is, by Jobs’ own admission, “not a product person, per se.”

The answer, Isaccson said Thursday, is that Cook — a cool, rational, operational wizard — is “joined at the hip” with chief designer Jony Ive — a sensitive, artistic type whom Jobs described as his “spiritual partner.”

Cook is the decider-in-chief, Isaacson said, but Cook and Ive working together “is like joining the two halves of Steve’s personality.”

It’s a tribute to Jobs’ leadership, Isaacson said, that “he ended up with the most loyal management team of A players of any corporation in America. That doesn’t mean a generation from now someone can’t screw it up — just as they almost screwed up Disney (DIS) a generation after Walt Disney died.”

Isaacson made his remarks at a breakfast conversation hosted by Fortune Magazine editor Andy Serwer. After appearances on everything from 60 Minutes to The Daily Show, there was not much Isaacson could say that he hadn’t said before. In some ways, the questions he ducked were as interesting as the ones he answered.

• He declined to share what Jobs’ widow, Laurene Powell, had to say about the book.
• He admitted to leaving some personal details out of the book, but declined to say what they were. That said, some of the descriptions he did include — such as Jobs spending his last days in his bedroom, on morphine-based medication, watching television — are painful enough.
• And to his regret, Isaacson was unable to shed more light than he did in the book on what exactly Jobs meant when he said he’d “finally cracked” the problem of how to make an integrated television interface. “I was more interested in his ideas about how to make textbooks free,” Isaacson admits.

During the two years they worked together on the book, Jobs grew increasingly emotional and intimate, Isaacson said. “There were many times when you’d look up and he’d be crying.”

“I found him mesmerizing. I became very emotionally attached to the man. I’m very sad.”

Below: Isaacson, Serwer and friends ringing the bell at NASDAQ, which provided the venue for Thursday’s breakfast.

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