Although it was never a guarantee until after ANH became a success, Lucas always intended (or at east hoped) for SW to be a series. The first couple of drafts (as mentioned above) had an end-crawl promising a sequel, and early drafts even included “Episode 1” and “Saga 1” in the title. Lucas even hired Alan Dean Foster to write a low budget sequel (“Splinter of the Mind’s Eye”) before the film was released, which he of course scrapped once it became a huge success and he decided to do a proper sequel instead.