The Sorcerer Supreme will return.
Doctor Strange had it all planned out. As he turned into ash and disappeared, Strange let Tony Stark know it was the only way. While comic book readers and smart moviegoers were not completely shocked by the death of so many Marvel characters, they will be the first to tell you that death is never permanent in the world of Marvel. According to a report by Mirror (so let's take it with a grain of salt, their Marvel rumors have been hit-or-miss), Benedict Cumberbatch will be returning for Doctor Strange 2.
The report claims that Cumberbatch is set to receive a $9.5 million salary for the sequel, which is $6 million more than what he made for Doctor Strange. Apparently, Marvel realizes that Strange, Captain Marvel, Black Panther, and Spider-Man will be their featured heroes going forward after stars like Captain America, Iron-Man, and possibly Thor leave the franchise. Cumberbatch will next return as Strange for the still-untitled Avengers 4 film. After that, plans for the MCU have been kept under wraps. Mirror reports that Doctor Strange 2 will start filming next year, if everything goes according to plan. We do know Spider-Man: Far From Home is being shot in the UK currently, while Black Panther 2 is in pre-development. A Guardians of the Galaxy 3 is planned for the future as well, although the James Gunn drama may delay the release. Other than that, the future of the MCU is a mystery.