A lot has been written about the feud between Vin Diesel and Dwayne Johnson that got started while filming The Fate of the Furious. Now, Dwayne Johnson has spoken more about what actually happened. Ultimately, it came down to the pair simply having different approaches to how they do the job. The issues between the two actors apparently got so bad, that even when they had a scene together in the most recent Fast and Furious film, they were never actually on the set at the same time. According to Johnson...
That is correct. We were not in any scenes together. Vin and I had a few discussions, including an important face-to-face in my trailer. And what I came to realize is that we have a fundamental difference in philosophies on how we approach moviemaking and collaborating. It took me some time, but I'm grateful for that clarity. Whether we work together again or not.
The question of whether they work together or not didn't seem to really be a question, as there are at least two more main franchise entries in the Fast and Furious series planned, but other comments by The Rock show that it is not a foregone conclusion that Dwayne Johnson's character of Hobbes will be back in the main series. There is currently a spinoff film set to star Johnson and Jason Statham, but it seems that after that, the future of The Rock in that franchise is up in the air.
Dwayne Johnson has spoken some before about the different philosophies that the two had regarding filmmaking. It sounds here, as Johnson tells Rolling Stone (via The Hollywood Reporter), like the biggest issue for Johnson was one of expectation. Because of the way that he approached the job, he had problems with Vin Diesel's different approach. Now, thanks to the "clarity" that Johnson has after the two talked about it, he at least has an understanding of how Diesel works, which will be a benefit if the two ever actually do work together again.
Of course, that doesn't mean the two actually like each other now that they've talked things out. It sounds like the bad blood is still there, which may make the two filing Fast 9 together difficult. The Fate of the Furious benefitted from a plot line which saw Vin Diesel separated from the rest of the team for most of the movie, making it easy for Dwayne Johnson and Vin Diesel to avoid each other. Perhaps the Hobbes and Shaw spinoff can set up a reason for Johnson's character to be in the next installment, but working on his own, giving them another easy out to prevent these two from getting on each other's nerves.