Cameron and Miller interviewed by The Hollywood Reporter, including a video of that interview;
THR: Tim, you had a lot of heat coming off of Deadpool, and instead of doing something that is not based on pre-existing material, you decided to do this. Why this?
MILLER: To some degree, all the stories that I love are based on pre-existing materials as either a book I love or a movie I love. And I don’t make a whole lot of distinction between those two things. Story is story. I mean, I wanted to make Deadpool 2. I was going to do that, until I wasn’t. So, there was that, which took up about seven months of my time. But even then, David and I were talking, like afterDeadpool 2, it was going to be this [Terminator].
THR: So, we can thank Ryan Reynolds for you doing this?
CAMERON: Thank you, Ryan.