Marvel Cinematic Universe movies get sequels, always. It's a law as old as time. And Doctor Strange won't be an outlier, to the delight of first-time MCU director Scott Derrickson. The man behind The Exorcism of Emily Rose and Sinister already has plans for Doctor Strange 2, telling Den of Geek:
"I love the character, I love the visual possibilities, and I know the comics so well—[the first movie is] the tip of an iceberg. There's so much progress that can be made. ... What made [Christopher Nolan's] The Dark Knight so great was that the origin story of Batman had been well-told, and then it was time to bring in a villain where you really got to go deep. And not just the Joker, also Two-Face. It was a more visceral experience, I'd love to be able to do that for Doctor Strange."
Can't go wrong, using that flick as a signpost. Just don't take inspiration from literally anything DC is doing these days, though.
Star Benedict Cumberbatch (Sherlock, Star Trek Into Darkness) vaguely revealed in August that he's got more than one Doctor Strange movie in his contract. He will also appear in at least one of the two upcoming Avengers movies.