Director John Carpenter commented just before the release of Escape From L.A. (1996) that IF this movie was successful then he would consider a third movie and that the only place left for Snake to escape from would be Earth. "Escape From Earth" was just an idea - Carpenter never even gave that title, it's just something people assumed it would be called.
Escape From L.A. evidently was not a commercial success and so the idea of a third movie went no further than Carpenter's comment.
