James Wan, who brought Furious 7 to the magical $1 billion mark, made it clear that he needed a break from the franchise after that production left him physically exhausted. He also wanted to get to work on a follow up to his haunted house story The Conjuring, and so ruled himself out.
Universal are reported to have gone back to Justin Lin who directed some earlier installments of the franchise but he's unavailable due to engagements with the Star Trek sequel. This could leave the door open for a very famous and long-standing cast member of the Fast & Furious series to take the helm...
Yes, strange as it may seem, the name being whispered at the minute is Vin Diesel, something which won't sit well the studio given his lack of experience behind the camera. Diesel has been a producer now for some time on the franchise and wants to try his hand at directing, but with a property as big and as lucrative as this one, no studio would want to leave all that in the hands of an unproven talent.
Add to that rumours that Diesel was difficult to work with on the set of the last movie, questioning directing calls and demanding late night script rewrites, and you have potential for a very big bust-up between effectively the star of the whole franchise and the studio hoping to keep it alive.
Of course all of the above is still firmly in the speculation bracket right now, but with an April 2017 release date drawing nearer every day, this is one production that the studio will want to kick start sooner rather than later.