I AM LEGEND prequel becomes sequel?

According to a source at AICN, Warner Bros. have decided to scrap the idea of an I AM LEGEND prequel because of it's story limitations (i.e. we know exactly where it is going) and will instead go in the direction of a sequel. Which is fine but as you may remember, Will Smith's Robert Neville didn't exactly make it out alive of the first movie and without him, do you even have a franchise to spawn a sequel from? It was Will Smith after enjoying immensely his time working on the first picture who came up with an initial prequel story that would win him another go as this character. But Warner Bros. are now balking at that and have told D.B. Weiss to focus on writing a sequel and a continuation of how the last movie ended. A lot of creative meetings and discussions ahead for this one. Personally, if they are desperate to carry on this franchise then I can't help but feel the only direction they should take is a duel storyline... something that shows Will Smith's downfall as he realises he is becoming the last man alive as the deadly virus spreads which can run concurrently with a new storyline set around the band of survivors from the first movie. Or go the BENEATH THE PLANET OF THE APES idea and forget the star (in that case Charlton Heston) except for a few very brief scenes (in this case maybe flashbacks) and hire someone with the stature to carry on the franchise. That was something the APES franchise never managed, replacing Charlton Heston. Can WB, replace Will Smith?