Paul Walker had shot most of his scenes before his untimely demise. He will be digitally recreated using advanced CGI technology, utilizing both Cody Walker and Caleb Walker as body doubles. The original screenplay was altered so that Walker's character Brian O'Conner could retire and head off into the sunset, as opposed to dying on screen. How will that affect future sequels? Apparently, Cody will play Brian O'Conner's never-before-mentioned brother in a role that will pretty much replace O'Conner, with this sibling joining Dom and his team.
Cody Walker talks about standing in for his late brother in this AP interview from a few months ago.
Cody Walker joining the Fast & Furious franchise cast has not been confirmed by Universal Pictures at this time. As of now, it's a purely speculative rumor.
A source close to the production had this to say,
Brian O'Conner, his wife Mia and their young son will literally walk into the sunset at some point in Fast & Furious 7. Cody Walker was recently spotted shooting scenes on the beach with co-star Jordana Brewster, who is likely leaving the franchise as well. They shared a tender embrace on the beaches of Malibu in one of these parting shots. To see those set photos:
If this story is true, expect Cody Walker's O'Conner brother character to be introduced during the climax of Fast & Furious 7.
Fast & Furious 7 comes to theaters April 10th, 2015 and stars Dwayne Johnson, Jason Statham, Michelle Rodriguez, Vin Diesel, Paul Walker, Kurt Russell, Jordana Brewster, Lucas Black. The film is directed by James Wan.