His name hasn't come up in any earlier reports, but THR is saying that Michael Shannon (Man of Steel) may be the front runner to play Cable in Deadpool 2. The report says that Shannon tops a list that also includes David Harbour (Stranger Things), but Kyle Chandler whose name has been mentioned was never a serious contender.
The thing that could hold up the casting is that Shannon has just signed on to another film, What They Had, which starts shooting this spring. He recently wrapped shooting on Horse Soldiers, in which he appears with Chris Hemsworth and Michael Pena.
David Leitch (John Wick) is directing and of course Ryan Reynolds is returning as the Merc with the Mouth. Zazie Beetz has signed on to play Domino. The film is scheduled to start shooting in Vancouver this summer.