With Avengers: Infinity War nearing its release, the Marvel Cinematic Universe is drawing closer to the climax it's been building toward for ten years, after which, nothing will ever be the same.
Thanks to Marvel Studios president Kevin Feige, we know the next phase of the MCU won't have an overarching story. We also know Marvel has no intention of putting any kind of a stop on its many franchises. And while Iron Man may not star in a solo film after the next Avengers, there are a lot of newer superheroes that will, such as Captain Marvel, Black Panther and Doctor Strange... maybe.
In a recent interview, Benedict Cumberbatch was asked about whether he knew when filming for the Doctor Strange sequel would begin, to which the actor stated, "Not at the moment, no. The masterplan is continually in flux, so it would be out of order for me to speculate" which implies that as of yet, there are no solid plans for a sequel, which may actually be a good thing.
When you look back at all the sequels the MCU has given us, you'll find that some of them were actually really unnecessary. It's obvious in the way many of them failed to capture the same kind of refreshing or fun qualities that made their predecessors so enjoyable. It's a consequence of Marvel Studios (like most film studios nowadays) being so sequel-oriented.
From the perspective of a film studio, it makes sense that the critical and financial success of a film means a sequel is warranted, especially when you have as many stories to choose from as comic book-based franchises do. However, creating a sequel for its own sake often comes at the cost of quality and yet, with the exception of The Incredible Hulk, Marvel has followed every single one of its films with a sequel, most of which ultimately added little to the overall mythos.
Take Thor: The Dark World, for example, which did very little for its characters or the overall plot of the MCU. Yes, it gave Loki the means to escape and very quickly-- and clumsily-- set up the death of Odin, but none of that required an entire film to set up. The majority of Thor's story had already been told through Thor and Marvel's The Avengers. Nothing significant would concern Thor until the events of Thor: Ragnarok, which successfully explored the relationship between Thor and Loki and managed to provide substantial changes, both emotionally and physically, for each of the film's characters. In short, the second sequel worked, but the first remains wholly unnecessary.
Doctor Strange tied up a lot of loose ends by the end of its third act. Strange understands magic, he's the new sorcerer supreme and he's on a path of self-improvement. Of course we want to see more but that doesn't necessarily mean we should. The way he defeated Dormammu was creative and unlike anything we'd seen before when it comes to heroes taking down their adversaries. A sequel is more than likely to include Baron Mordo, who seemed to be on a campaign to rid the world of anyone that disturbed the natural law.
There's a small chance that a sequel would be written in such a way that Doctor Strange would be able to find a way to defeat Mordo that's equally as innovative and unexpected as his confrontation with Dormammu -- but it's unlikely. Which means anyone who has been following the Marvel Cinematic Universe thus far can expect the more typical CGI final battle between two similar characters.