Omaha, Nebraska (


) -- Warren Buffett may be the top investor of his generation, but it is

Berkshire Hathaway's

(BRK.B) - Get Report

strong earnings outlook that may cement the "Oracle of Omaha" as a market wizard for the ages.

Some of this generation's most prominent investors close their funds to outside money, for instance hedge-funders Stanley Druckenmiller, Carl Icahn and George Soros, while others such as Bill Gross of bond giant


question whether

the smartest minds on Wall Street

simply benefited from an advantageous era to make investments.

Also see:

Berkshire Hathaway Operating Earnings Rise 42%

But even if Gross' point has merit, Buffett's legacy is likely to surpass his peers by way of Berkshire Hathaway's long-term prospects.

Gross, chief investment officer and co-founder of Pimco, the world's top bond manager,

made headlines in April

when he questioned whether famed investors, such as Buffett, Mario Gabelli of

GAMCO Investors

, George Soros of

Soros Management

, Leon Cooperman of

Omega Advisors

, Ray Dalio of

Bridgewater Management

, Howard Marks of

Oaktree Capital

, Peter Lynch of the

Fidelity Magellan Fund

and himself, really deserved credit for strong returns given their investment records occurred in a generation marked by falling volatility and easing interest rates.

Also see:

Berkshire Hathaway Operating Earnings Rise 42%

Ultimately, Gross wondered how the aforementioned

investing titans

would have fared in another age.

Would their returns have been so spectacular? Did they deserve monikers like the "Oracle of Omaha" and the "Bond King?"

Also see:

Doug Kass To Throw a Few 'Curveballs' At Warren Buffett

"My point is this: PIMCO's epoch, Berkshire Hathaway's epoch, Peter Lynch's epoch, all occurred or have occurred within an epoch of credit expansion -- a period where those that reached for carry, that sold volatility, that tilted towards yield and more credit risk, or that were sheltered either structurally or reputationally from withdrawals and delevering (Buffett) that clipped competitors at just the wrong time -- succeeded," Gross



"What if perpetual credit expansion and its fertilization of asset prices and returns are substantially altered? . . . Ah, now, that would be a test of greatness: the ability to adapt to a new epoch," Gross added.

Also see:

Doug Kass To Throw a Few 'Curveballs' At Warren Buffett

"The problem with the Buffetts, the Fusses, the Granthams, the Marks, the Dalios, the Gabellis, the Coopermans, and the Grosses of the world is that they'll likely never find out. Epochs can and likely will outlast them."

Gross manages 25 U.S. mutual funds with combined assets of $373 billion, according to


and was ranked the bond manager of the decade by



While Gross, a so-called 'bond king,' is right to question his returns in an era of falling interest rates, and those of his hedge fund counterparts given their access to cheap leverage, he may miss the mark when it comes to Warren Buffett.

>>Also see: What Would Ben Graham Buy? >>

Buffett, by way of over 80 operating subsidiaries at Berkshire Hathaway including a sprawling insurance operation, recent acquisitions such as

BNSF Railways



and fast-growing units like

MidAmerican Energy




Marmon Group

, will see his investments tested in a new epoch.

Were Buffett to announce his exit from Berkshire tomorrow -- he won't -- the "Oracle's" wizardry will be bench-marked by way of Berkshire Hathaway's earnings and its performance relative to the S&P 500.

As a result of the momentum Buffett has imparted on Berkshire by way of acquisitions, careful allocation of capital among operating subsidiaries and an investment portfolio that's leveraged to U.S. and international growth by way of stakes in


(KO) - Get Report


Wells Fargo

(WFC) - Get Report



(IBM) - Get Report

, some investors are almost indifferent to succession plans for the long-time Berkshire head.

Shareholders are investing in Berkshire's ownership of operating businesses and the leverage that the company should get from the next five-to-10 years of economic improvement, according to William Smead, chief investment officer of

Smead Capital

, an investor in Berkshire's B-shares.

Smead expects Berkshire will sustain compound internal growth rates of about 15% annually for years to come.

Mario Gabelli of GAMCO Investors said earlier Friday on


he expects Berkshire's internal book value growth to slow from historic rates of about 20% annually to 10% annually. Still, Gabelli expects a 10% book value growth rate to outperform high single digit gains posted by the

S&P 500


For his part, Warren Buffett is concerned about Berkshire Hathaway's potential underperformance under his watch.

At the beginning of Berkshire's 2012

annual shareholder letter

, Buffett lamented an underperformance of Berkshire's book value growth relative the S&P 500. He fears the firm's five-year book value growth rate may underperform the S&P 500 for the first time ever.

"To date, we've never had a five-year period of underperformance, having managed 43 times to surpass the S&P over such a stretch. But the S&P has now had gains in each of the last four years, outpacing us over that period. If the market continues to advance in 2013, our streak of five year wins will end," Buffett wrote.

In 2012, Berkshire's book value per share increased 14.4%, behind the S&P 500's gains of more than 15%.

>>Also see: Doug Kass: Analyzing A Successful Trio Of Trades >>

Were Berkshire to perform below Buffett's goal posts in 2013, he indicated considering a dividend for the conglomerate, however, shareholders

generally dismiss

the prospect of such a move.

Buffett's legacy is a hot topic heading into Berkshire Hathaway's

annual shareholder meeting

on May 4, given uncertainty surrounding a successor to run the conglomerate with a market capitalization approaching $270 billion.

"I think the succession question will be obviously front and center," said Thomas Russo, a partner at

Gardner, Russo & Gardner

in an April interview. "I gather there will be some commentary."

In late 2011, Buffett also said his son, Howard Buffett, will

succeed him

as a non-executive chairman of Berkshire to oversee a maintenance of the firm's values.

Less clear is who would be chief executive of Berkshire Hathaway. Currently, speculation centers on insurance unit head Ajit Jain, BNSF railroad CEO Matthew Rose, MidAmerican Energy CEO Greg Abel as leading candidates to be Buffett's successor.

Buffett has informed Berkshire Hathaway's board of directors of his successor.

Russo, the Berkshire investor, sees room for multiple job openings to replace Buffett, when the time comes. He expects up to four roles to fit the shoes of Buffett.

Gardner, Russo & Gardner is Berkshire's tenth largest shareholder with a stake of nearly $800 million in the company's Class A shares and over $200 million of Class B shares, according to


data. Russo says Berkshire holding's represent about 11% of the firm's assets.

While succession and Berkshire Hathaway's performance as the conglomerate grows in size both stand out as uncertainties heading into the company's annual meeting, they also may eventually prove Buffett's greatness.

Buffett likely has many years left at the helm of Berkshire to cut acquisitions and fire his elephant M&A guns before he passes the reins to a successor. Unlike his hedge fund and mutual fund contemporaries, however, Buffett's track record will be tested long after he's left Berkshire.

-- Written by Antoine Gara in Omaha, Nebraska.

Follow @antoinegara