It appears that Michael Shannon is the frontrunner to portray Cable in Deadpool 2.
Variety first reported the news, noting that he has been Fox's top choice for about a week. No official casting choice has been made and Fox has also no commented on the rumor. Zazie Beetz was recently cast as Domino and fans are surely the casting of fan favorite Cable is highly anticipated. There is no production date or official release date at this moment, so this could be the final piece in the proverbial puzzle.
Personally, I think this is a fine choice. Shannon is a talented and versatile actor who has shown a wide range of character and career choices. His list of credits include Man of Steel, Mud, Take Shelter, Machine Gun Preacher, The Iceman, Midnight Special, and the Afghan war drama Horse Soldiers. He’s received Academy Award nominations for best supporting actor for Revolutionary Road and Nocturnal Animals.