NEW YORK ( TheStreet) - What if Warren Buffett and Carl Icahn retire in 2013? While neither Berkshire Hathaway's ( BRK.A) "Oracle of Omaha" nor Icahn, who runs Icahn Enterprises ( IEP), have shown any indication of slowing, the thought is in the back of investors minds and it begs the question of who will be the next generation of Wall Street leaders. For decades, Buffett and Icahn have been a sort of yin and yang when it comes to investing style, and their outspoken ways have been a compass for many investors. Buffett, who champions stock investments with a holding period of 'forever,' is an oft-cited as ambassador of long-term investing and his annual letteris required reading for many. In contrast to Buffett, Icahn has never been known as a patient type. While some follow Buffett's holdings for potential stocks to pay for a child's college education, investors key in on Icahn's activity for corporate breakups, board ousters and takeovers that create instant shareholder value. During the dot com bubble, Buffett avoided high flying tech stocks in favor of tried and true names like Coca-Cola ( KO) to the scorn and then admiration of others. In the financial crisis, Buffett stepped up as the most credible advocate of equities through the stock market selloff and eventual recovery. Multi-billion dollar investments in Goldman Sachs ( GS) and General Electric ( GE) were seen as an example of savvy investing and public service, and put Buffett's imprimatur on both companies at a time of critical need. Icahn, who takes a more standoffish stance with companies he invests in, nevertheless draws a similar amount of respect among investors. First called a corporate raider in the takeover of now-defunct airline TWA, Icahn's gone on to become known as a scourge of corporate cronyism, shareholder destruction and C-Suite mismanagement. In the wake of Time Warner ( TWX) and AOL's ( AOL) disastrous merger, Icahn drove the breakup of the dysfunctional media monolith and his actions can be seen as driving each company's newfound success, and that of Time Warner Cable ( TWC). Icahn drove the split up of Motorola ( MOT) and his prying on intellectual property assets were seen as a key driver of Motorola Mobility's eventual acquisition by Google ( GOOG), just as handset struggles hit the likes of Research In Motion ( RIMM) and Nokia ( NOK). In 2012, Icahn's been a key to the realignment of Chesapeake Energy's ( CHK) board. Still, while Buffett and Icahn may have an enduring impact on the investing world and some of America's top companies, neither man will stay in the game forever. In 2012, Buffett and Icahn showed their biggest signs yet of transition. Buffett formally said his son Howard would be Berkshire's value guardian and he indicated that the investing conglomerate has found a replacement for the legendary value investor. On a far more serious note, Buffett said in April he has a treatable form of prostate cancer, while reiterating his love of the job and lack of slowing. More recently, Buffett increased the price at which he's willing to buy Berkshire shares back, an option the 'Oracle' been hesitant to do given his track record of outperforming the S&P 500. In 2011, Icahn formally closed his hedge fund Icahn Capital to outside money and in 2012, he set aside $3 billion for his son Brett Icahn and a portfolio manager David Schechter. Still, recent moves like Chesapeake Energy and a large stake in Netflix show he's willing to make big new investments. The question of what would happen were Buffett and Icahn to retire raises crucial points. Who are the next generation of investing leaders and how may they be different than the value and activist approaches championed by Buffett and Icahn respectively? The answers aren't easy. In recent years, legendary investors like Stanley Druckenmiller of Duquesne Management, George Soros of Soros Management and others have all closed shop to outside investors. Meanwhile, once high-flying hedge funders like Philip Falcone of Harbinger Capital Partners and John Paulson of Paulson & Co. have fallen on hard times. Below are four recommendations of a next generation of investors, were Buffett and Icahn to go from hunting investing green to the golf course.