I Am Legend 2 is finally in the works, but to succeed, it will need to repeat and improve upon the successful elements of the first film. A post-apocalyptic movie with only one main character and an otherwise abandoned city full of zombies/vampires/Darkseekers could easily have flopped, but I Am Legend managed to pull it off. This can, of course, be attributed to Will Smith's performance as Dr. Robert Neville – the supposed last man on Earth. But, additionally, it was a combination of other factors that made the film so memorable, something I Am Legend 2 can duplicate.
https://screenrant.com/i-am-legend-sequel-repeat-original-ideas-success/