I Am Legend 2 will bring back Will Smith's character, Robert Neville, by following the first film's alternate ending in which he lives – but this still presents a problem. The long-awaited sequel to the 2007 I Am Legend movie is intended to align more closely with the novel by author Richard Matheson. Though the book does follow the plot line in which Neville discovers that the vampires, or Darkseekers as they are called in the movie, are capable of emotional connection, it ends with the character's death. So now, the direction forward is unclear.
https://screenrant.com/i-am-legend-2-will-smith-character-sequel-problem/