After "Furious 7" became the fifth highest-grossing movie of all time, it seemed possible the franchise would drive on and on into infinity. But Vin Diesel is pumping the breaks -- somewhat. The actor recently posted a Facebook message to say that no directors have been given an offer to make the eighth "Fast and Furious" movie. More importantly, he dropped this nugget: "I promised the studio I would deliver one last trilogy to end the saga."With Universal's plan of 10 films in the series, that implies we have three more installments to anticipate, starting with "Furious 8" scheduled for April 14, 2017. Diesel wrote that the reason none of them have a director is because "this is too special a franchise, so these matters have to be very carefully handled." Behind the scenes, however, reports indicate everything may not be quite so sunny. Diesel posted the note two days after a Hollywood Reporter article rehashed the challenges of making "Furious 7," which took a toll on director James Wan's health, in part, sources reportedly say, because "Diesel proved extraordinarily difficult." (Wan passed on directing "Furious 8" so he could helm "The Conjuring 2.") Diesel is said to have held up production by questioning tiny details and holding late-night script sessions. Now, according to THR, some at Universal Pictures "fear" the actor might want to direct a "Furious" movie himself. Regardless, Diesel, who has been one of the franchise's producers since its fourth installment in 2009, promised his next Facebook post will announce the directors (plural). He didn't say when that would happen, but he did include a photo of himself grinning.