Silverbolt is still out there. He can be an a CG bot but I have this sinking feeling that Silverbolt won;t be in it because at this point we've seen hints of most if not all major character. Unless Silverbolt is a game-only character, who do you think Avery could voice if he is indeed in the film? I remember people thought he could be Sentinel Prime but that's been dismissed with the return of Leonard Nemoy. Personally I could see him as Leadfoot.