Many millions of dollars are at stake, considering the franchise has sold $2.6 billion in tickets around the world since 2001. But the filmmakers have to be careful in deciding how they bring Walker's character to an end in the series, unless they replace him with another actor.
Walker, 40, and the rest of the cast were on a short break for Thanksgiving when he stepped into a red 2005 Porsche Carerra GT for a short ride around a Santa Clarita, California, business park Saturday afternoon. Investigators believe the car, driven by Walker's friend Roger Rodas, was speeding when it clipped a light pole and was engulfed in flames, killing both men.
Man arrested for stealing part of Paul Walker Porsche wreckage
Universal Pictures confirmed Tuesday that they've put production on hold "for a period of time so we can assess all options available to move forward with the franchise." A well-placed source shared details with CNN about what's gone on behind the scenes.
Walker had been set to fly back to Atlanta by Monday for the resumption of filming. Filming, which began in the Georgia capital three months ago, was already behind schedule and only about 50% completed, according to the source.
His death left the producers, cast and crew in confusion, the source said.
Editors began reviewing frame by frame what had already been shot with Walker, including outtakes, for footage that might be incorporated into a rewritten script, the source said. They were looking for ways to piece together new scenes with Walker, perhaps using computer-generated imagery, or CGI.
The script writers have been considering how to rewrite the story to end Walker's character.  If O'Conner is killed off while street racing -- a key element in each film -- Walker's fans could be offended.
Stars who died during production
Without a creative answer, producers could be forced to start over without Walker's character, possibly delaying the film that Universal counted on to be a tent pole for its summer releases.
Universal Pictures executives flew from Hollywood to Atlanta where they met Wednesday night with the producers and crew to discuss the possibilities.
Executives with the insurance company that bonded the production are also involved in the decisions, the source said.
Until decisions are made, the production crew is out of work with no idea how long the shutdown will last. They will be paid until Friday, when they are suppose to leave Atlanta, the source said.
The plan to send the cast and crew to Abu Dhabi for filming is also on hold, the source said.