At the same time it was revealed Lucas Black would be returning to the Fast & Furious franchise for the first time since Tokyo Drift, we learned he'd be hanging around for three movies, all the way through Fast & Furious 9. That may seem like a long stretch but Universal has to be happy with the $2B series Vin Diesel built, so obviously they want it to go on as long as possible. But if they are concluding it with the ninth chapter, the guy they want at the helm is the one who reinvigorated it: Justin Lin.
Lin directed the last four movies, including last year's Fast 6, before stepping aside to pursue other projects. James Wan (The Conjuring) took over for Furious 7, but now that he's leaving again for The Conjuring 2 that opens the door for Lin to return for what Deadline describes as "a multi-part production that will lead to multiple movies shot together and will wave the checkered flag on the Fast & Furious franchise." Lin had agreed to direct a sequel to The Bourne Legacy but with that film getting bumped aside due to the return of Matt Damon and Paul Greengrass, it leaves a bit of room in Lin's schedule.
This is all just rumor for now but one has to believe Lin would want to finish up what he started. Fast & Furious has always been about family, and Lin is definitely a big part of that.
