I recently had a chance to talk with Warren Buffett biographer Alice Schroeder, author of The Snowball: Warren Buffett and the Business of Life.  In this final part of a five-part interview, I ask her about Berkshire Hathaway (NYSE: BRK-A) (NYSE: BRK-B) post-Buffett.

Mac Greer: Let's talk about Warren Buffett's successor. If you had to say right now, who is the frontrunner?

Alice Schroeder: I think that things are now in flux, because Warren has put Steve Burke on the board from Comcast (Nasdaq: CMCSA). He's got Matt Rose now from Burlington Northern, and David Sokol, who was turning around NetJets in three months; it's taking much longer than that. He's got a lot at stake there. I don't think there is a frontrunner now. I think more than any time since I have known Warren, or in the past history of Berkshire Hathaway, I think it is less clear who would succeed Warren than it has ever been.

Mac: Is there a dark horse?

Alice: Yes, there is, but I can't tell you.

Mac: How about "rhymes with"?

Alice: (Laughs) I continue to believe that the board, in order to fulfill its fiduciary responsibilities, must look outside the company. I've mentioned Byron Trott in the past, because I think he would be terrific, but he's not the only one outside the company. Byron Trott was the former Goldman Sachs (NYSE: GS) investment banker who served Buffett so well. Warren thinks he is terrific. He understands how to allocate capital and is the kind of person that I think could rally the managers. I don't necessarily think it will be him, but he's the sort of person that they could look outside the company. I'm not saying there is no one qualified within Berkshire. The managers who might have aspirations will be reading this, and be all mad at me. There are possibly some people within, but Warren typically hires people who are operating managers, not capital allocators.

Mac: And in this succession vein, it's a question that we don't really hear asked very much, but who succeeds Charlie Munger?

Alice: Nobody. He is beyond irreplaceable. I am sure there will be a vice chairman, but the role of the unique personality of Charlie Munger? He's one of a kind. Warren is one of a kind, too. But someone has to succeed Warren, but no one has to succeed Charlie. There won't be anybody.

Check out the first four parts of our interview:

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Mac Greer does not have a financial position in any of the stocks mentioned in this article. The Motley Fool has a disclosure policy.