James Cameron is back on board as director as well.
Also on board for the three movies is Stephen Lang who played Marine Colonel Quaritch.
The plot for the movies are kept under wraps, however back in October it was revealed by Worthington during an Australian radio interview that principal production will begin in October 2014.
It was also reported by The Hollywood Reporter that Sully (Worthington) and Neytiri (Saldana) have kids.
Cameron revealed last summer that he would create three sequels instead of two. On board for the series are screenwriters Josh Friedman, Rick Jaffa, Amanda Silver, and Shane Salerno. Cameron also announced that science fiction author Steven Charles will write four stand-alone novels based on the making of Avatar, as well as stories for Cameron's three sequels.
According to the film’s website, the sequel will be released in December 2016, the third in December 2017, and the final installment in December 2018.