Just a heads up, possible spoilers about Mordo Doctor Strang here.
Doctor Strange 2 seems like an inevitable sequel for the MCU. It's hard to know exactly how integral he is going to become to the overall universe, but I think another solo adventure is incredibly likely.
You can see the film is already beginning to sow the seeds for the future too, as Mordo is a 'good' guy in the film. This is likely leading to the character turning on Strange sometime in the future. Director Scott Derrickson spoke about this with ScreenRant in a new interview where he talks about his decision to start Mordo at this point in his journey. He said:
Yeah, in the case of Mordo, in the comic books, that character was just really arch. You know, just really arch and he's in the origin issue and even in reading through – and I've read the entire body of Doctor Strange now – it was a difficult character, very difficult character to adapt. Because of the very basic archness that he plays all the way through there. So we wanted to keep what were the interesting aspects of him (his relationship with The Ancient One) but the only way that Mordo, who needs to be a presence in the universe of Doctor Strange and God willing, in sequels, I felt that we had to start by establishing who he was before he got into that arch villainy in the comics. And that's a lot of what we're doing in this movie is we're sort of building a foundational understanding of who he was before the guy that you met in that comic so that that turn isn't an arch turn.
This seems a reasonable and fine enough explination as to why Mordo is where he is in the movie. I'll tell you what though. Sign me up for a villainous Chiwetel Ejiofor tearing up the screen in the future.