He would have used special Sarutobi medical ninjutsu for Sasuke and Kakashi's recovery. Thus making them full powerhouses, Sasuke wouldn't have gone to Orochimaru and Kakashi would have got his 2nd MS by the end of part 2.
Also:
*Tsunade would end her days gambling, or sweeping Hiruzen's floor
*Naruto < Sasuke
*Kaguya would have died by the simple fact that Hiruzen splitted his chakra
*Hidan would have become mortal
*Naruto would have had his Bijuu removed w/o dying, Kurama becoming The Professor's pet
*Jiraya would have seen Naruto becoming a mere servant of the Double Rinnegan Master, Sarutobi Sensei
*The Otsutsukis would have been referred as the wannabe Sarutobis
*Hiruzen would have made Sakura relevant to the story(although a bit of a short story)
*Lord Third would have used the 9 gates to destroy Kamui, just for fun
*The Professor would have found Tobidara using Creation Of All Things