rascal said:
Obviously haven't read the book, but didn't Will Smith die in I Am Legend?
Just like 300, the original film was so wildly successful compared to projections and hopes, that a prequel was discussed between Francis Lawrence and Will Smith. It would have covered the timeline after the helicopter crash on the bridge and before you see him three years later. Some of the rumors were that Emma Thompson would reprise her role and that half the movie would be about a convoy run and the other half would be the defense of the last military facility on the east coast, where the last hope for a cure was held. Two of the major plot points was that Smith's role as a scientist had actually made some aspects of the plague worse and the other was that the last half of the movie involves the lengths the rest of the humans go to keep Smith alive. Which explains some of his survivors guilt in the original.
Pitt had seen a few of the treatments and wanted to sell the unused combat footage to Warner Brothers to account for the early outline of a montage of world wide military failure to defend major cities. And how those major cities fell. My guess is it's a last ditch attempt to actually recoup some of the budget instead of having a massively expensive DVD extra. Any green lit Legend 2 would only purchased if Pitt costarred with Smith and took second billing and Pitt would sign on for Legend 3 ( would pick up where Alice Braga and the child reach the fortress in the safe zone) on his own as the lead.