Anthony Breznican freezes frames from new promo clip to get a closer look at The Rock as Roadblock, Adrianne Palicki as Lady Jaye, and more; see his notes, add yours!
And here is our new bad guy, Firefly (Ray Stevenson, memorable as Pullo on HBO's Rome). There's no mention of the metal-faced Destro, or the Baroness, in the sequel, but again this silver masked man suggests Cobra Commander to me. Joseph Gordon-Levitt has said he is not returning as the character, but it's logical to assume he doesn't have to if we never see the character's deformed face. We never did on the cartoon.