Walt Disney Co. (DIS) - Get Walt Disney Company Report Chief Executive Officer Bob Iger will reportedly remain at the helm of the House of Mouse past 2019 if a deal with Twenty-First Century Fox Inc. (FOXA) - Get Fox Corporation Class A Report is reached, but he should know from his predecessor that he can't remain in that role forever.

The Burbank, Calif.-based mass media company with a market capitalization of $159 billion is closing in on a deal with the Rupert Murdoch-controlled media company to acquire its studio and television production assets, according to a report by CNBC. The enterprise value of the Fox assets is above $60 billion, CNBC said, citing unnamed sources. The Wall Street Journal, meanwhile, reported that the assets are valued at $40 billion.

Disney announced in March that Iger's contract would be extended until mid-2019, a year beyond his June 2018 expiration date -- and Iger said he was going to leave the company in 2019.

"This time I mean it," Iger said on Oct. 3 in Los Angeles at a media industry conference hosted by Vanity Fair.

The company also said that he will serve as a consultant for three years after that, receiving $500,000 for each of the first eight quarters and $250,000 for the last four in exchange for access to his "unique skills, knowledge and experience with regard to the media and entertainment business."

Now, according to a Wall Street Journal report, Iger will likely stay past his 2019 retirement date if Disney can ink a deal with Twenty-First Century Fox.

Iger, 66, was installed as Disney's chief executive officer in October 2005. His 12-year tenure surpasses the average CEO tenure of 8 years, according to executive search firm Korn Ferry.

"It makes sense that for large, complex companies, the executive who holds the highest leadership position would have more and diverse experiences, which would translate to more years in the workforce," said Tierney Remick, vice chairman of Korn Ferry's Board and CEO Services.

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If Iger were to remain the CEO of Disney beyond mid-2019, his tenure would still be less than his predecessor Michael Eisner, who held the top spot at Disney for 21 years, according to BoardEx, a relationship mapping service of TheStreet Inc.

Under Eisner, 75, Disney acquired the ABC broadcast network and added seven more theme parks, a cruise ship line, a stage play division as well as 10 domestic cable channels, including ESPN.

Eisner's later years at Disney were marred by a shareholder revolt that eventually forced him out of his chairman role and a bitter boardroom battle with Roy Disney and Stanley Gold, both of whom had lobbied to give him the top job in 1984.

Still, it is understandable that shareholders may want Iger to remain as CEO -- under his leadership, Disney shares have soared more than 340% and his presence would provide some continuity through this big deal. Recently, however, ESPN has weighed on Disney's earnings and is not the profit machine it once was, yet Iger is still "confident" in the network's future and the board extension of Iger's contract expresses the directors' conviction in his ability. (For comparison, Disney stock soared approximately 1974% between 1984 and 2005 under Eisner, according to data from Yahoo Finance, although shares began declining in 2000.)

While there are other parties interested in Fox's assets, Jefferies analyst John Janedis sees Disney as the more likely suitor given the regulatory concerns with a Comcast Corp. (CMCSA) - Get Comcast Corporation Class A Report deal. However, assuming Comcast has interest in the same assets as Disney, Janedis estimates the deal would be high-single-digit dilutive to Comcast earnings, versus neutral to Disney due to relative tax rates.

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Shares of Disney were holding relatively flat at $105.50 at around 11:00 a.m. EST during the trading session on Thursday.

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