In an interview with DesdeHollywood, Michelle Rodriguez (the 'dead' but apparently not Letty in the movies) confirms that Statham is, indeed, joining Vin Diesel and Dwayne Johnson for the next go-round.
Jason Statham, Vin Diesel, Dwayne Johnson, when you see these guys in a room you know they belong together [...] You can see in their eyes that they have gone through a lot [...] I applaud Universal for getting him on-board!”
...says Rodriguez HERE.
No word on whether the rest of Billy's HUGE POTENTIAL SPOILERS will come to pass. But with Statham in play, it's now looking increasingly likely that the rumored structure to the ending of FAST & FURIOUS SIX - its supposed connection to one of F6's characters and to one of the previous films - might end up shaking out as indicated.
We'll find out when FAST & FURIOUS 6 opens May 24.