Today’s revelation that Berkshire Hathaway Inc. had poached four top executivesfrom American International Group Inc. was big news all on its own. But it could also offer an important hint about a topic that’s a constant topic of speculation for Berkshire shareholders: who’s going to replace Warren Buffett.

The four new hires, experts at insuring large and unusual risks, are defecting from AIG to set up a new property-casualty unit at Berkshire that reports directly to Ajit Jain, the mastermind behind many of Berkshire’s past successes in the world of insurance.