In Deadpool's post-credits scene, Wade himself revealed that his on-again-off-again partner Cable is scheduled to appear in the sequel. As for who could take the role, 'Pool jokingly offered a few suggestions, including Mel Gibson, Dolph Lundgren, and Keira Knightley.
However, Avatar actor Stephen Lang has begun lobbying for the role on social media, posting pictures of his workout routine on Twitter and namedropping both Cable and Deadpool.
Even though neither of his arms appears to be bionic, Lang is as likely to get the role as anyone - after all, as Deadpool says in the stinger, all they need is a "big guy with a flat top".
Deadpool's sequel has reportedly already been greenlit, though no release date has been set. Cable would also presumably be a major part in the announced X-Force film as well.