In the alternate ending, it isn’t all about Dr. Robert Neville magically

 In the alternate ending, it isn’t all about Dr. Robert Neville magically

 fixing things with his miracle cure. Rather, there’s no cure to begin with, nor is there a gigantic grenade-induced death of Robert or the leader of the Hemocytes (Dash Mihok). Rather, Robert returns his female test subject to her mate, who has only been trying to retrieve his beloved. 

Robert, Anna and Ethan leave New York in I Am Legend’s alternate ending, with a radio message detailing their eventual position. Rather than a more action-packed ending that apparently tested better

 with audiences, this course of events pushes a theme that better fits the movie that came before it. It also opens those important doors that could make for an intriguing sequel.