The movie will be based on the actual story now, and not anything that conspiracy theorists have posted over the years. This is coming from people who are very much close with what's happening to the film. One popular idea was to have Kevin Sullivan be involved with the murders (a very popular conspiracy theory), but it got axed.

Regarding cast members who will play Benoit, Michael Hall was once suggested to play Benoit but his rep said he didn't want to play a killer and be typecast. Kellen Lutz and Liam McIntyre were also others brought up for discussion for the Benoit role but that's been a while back. There were also rumors of Liev Schreiber playing Benoit but those were nixed as well. 

WWE is reportedly unhappy with the idea of the movie being made. It's believed the movie will show drugs, perhaps steroids or others, along with CTE (Chronic Traumatic Encephalopathy) as a possible explanation for why Benoit did what he did.