My thoughts are that the war might not have lasted as long. Was he not known as an aggresive strategist? Examples are Pearl Harvbor, Coral Sea, and Midway. Could he have adapted himself to a purely defensive strategy? His death was somewhat the result of his wanting to be upfront and personal in the Solomons Campaign, no? His pursuit a Hitler-like decisive battle at sea might have brought Japan to defeat sooner, perhaps?