Given his love of his investment role - we don't expect Buffett to step down while he is fit and well, but considering his investment genius his answer certainly merits attention.
Here are a few resources on these three kings:
Seth Klarman
http://www.economist.com/node/21558274
This Economist article gives an excellent overview of Klarman's career
Greg Alexander
http://www.scribd.com/doc/19364402/Ruane-Cunniff-Goldfarb-Investor-Day-2009-Transcript
A transcript of a Ruane Cunniff & Goldfarb Investor day in 2009 includes contributions from Alexander among other members of the Sequoia team.
LiLu
http://cbs360.gsb.columbia.edu:8080/ess/echo/presentation/749b9e77-b822-456f-8784-9dff07518360
This legends of Value Investing video from Columbia Business School, recorded in Spring 2010, gives us a rare opportunity to experience a lecture from the man who manages Charlie Munger's money