Michael B. Jordan's role in convinced Will Smith to break his sequel rule and reprise his role as Dr. Robert Neville.
It's not yet known exactly how Smith's character will be making his reappearance in this much-anticipated sequel. At the end of I Am Legend, Dr. Neville dies in an explosive sacrifice against the zombie-like Darkseekers, which seems to be a definitive end for the character. It may be that in the sequel, he will appear only in flashbacks, where Smith would be put through the same de-aging technology that was used in I Am Legend novel's ending. However, the more burning question has to do with exactly what role Jordan will have in I Am Legend 2, and for an answer to that, it may be possible to look to the actor's history with Creed.
The first Creed movie was released in 2015 as a spin-off to the six-part Stallone reportedly not returning for Creed III, he has now officially ed the torch over to this next generation of films. With that, Jordan has managed to pull off his greatest trick, the gradual takeover of an iconic franchise.
In I Am Legend 2, Jordan may once again be playing the role of the student to a seasoned veteran, this time with Smith instead of Stallone. It's even possible that I Am Legend 2 will mirror Adonis Creed's back story even more closely by once again casting Jordan as the long-lost son. Either way, it is a fair bet that Smith will be taking more of a ing role this time around, perhaps even casting Dr. Neville as the antagonist, leaving room for Jordan once again to take a leading role in a follow-up series.
No matter what the exact details of the plot might be, it is clear that the make-or-break of the film's success will be strongly based on Jordan's ability to take over from Smith. If Jordan can once again prove his ability to be a follow-up success, it would not be unlikely for a third I Am Legend film to be made in the future in which Dr. Neville would not need to make an appearance at all. If I Am Legend 2 intends to set up a plot for further sequels, then the Creed model wouldn't be a bad example to follow.