Fans everywhere got massive nerdboners (even us lady-fans) during Deadpool's post-credits scene, where we got a little hint that Cable might be in the next Deadpool flick. Well, according to co-creator of Cable and creator of Deadpool—and all-around comics laughingstock—Rob Liefeld, Cable almost debuted in the first Deadpool film; but Liefeld actively fought against that happening.
According to an interview with Inverse, Liefeld said...
"Half of us believed the movie should involve Cable. I could feel Cable breathing down my neck. I said, 'No. Don’t put Cable in the first movie.' If Cable comes later, great. Deadpool is a vehicle for Ryan to shine. Cable bogs it down, I’m not sure it works as a first film with a general audience. I got in the car and I said, 'Did I really just kill the appearance of my other more popular character?'"
I'm not sure what universe it is that Cable is a more popular character than Deadpool, but it's probably the same alternate universe where Liefeld has talent and makes sense. Which frankly worries me because Liefeld's reason for not wanting Cable to debut in the first film makes a lot of sense. But hey, broken clocks, amirite?
20th Century Fox has announced that Deadpool is getting a sequel, but we're still awaiting confirmation that Cable will be in the second film.