Berkshire Hathaway has always been synonymous with Warren Buffett. Now, it is up to his eldest son, Howard Buffett, to keep the cluster culture alive. The announcement made on Friday that Warren Buffett, 96 years old, left the position of president of the company council means that the investment legend will no longer have a management role in the company he assumed in 1965, will not even act as regular advisor to Greg Abel, who succeeded him as…