Doctor Strange developed the Third Eye at the end of Doctor Strange in the Multiverse of Madness because he used the Darkhold to reach across the multiverse to possess another version of himself. The ending of the film is a victory for Doctor Strange, Wong, and America, each of whom did their part in trying to stop the Scarlet Witch from taking advantage of the multiverse for personal means.
Wanda Maximoff destroyed the Darkhold temple and all the versions of the book across the multiverse so that no one will ever be able to use the spells again. In Doctor Strange in the Multiverse of Madness, the Scarlet Witch was corrupted by the Darkhold and it would be repetitive for the MCU to do a similar storyline with Doctor Strange so soon after.
Doctor Strange in the Multiverse of Madness is the second solo outing for the sorcerer, who was gone for five years after the end of the world. The potential for Americsa Chavez to appear in a future project is high because the MCU is yet to explore her full range of powers. America Chavez, a multiversal with the ability to punch through any dimensions, was introduced in the sequel. Since his first appearance in Doctor Strange, Benedict Cumberbatch's character has traveled to space, battled Thanos, and opened the doors to the multiverse after a magic spell goes awry. Secret Wars, a comic book event that saw superheroes from various worlds duke it out on a planet called Battleword, was created from the remains of an incursion happening between two worlds. Doctor Strange in the Multiverse of Madness lays the groundwork for the rest of the MCU. Doctor Strange and Clea are trying to fix incursions that could lead them to He Who Remains, who is set to appear in an upcoming movie. When Doctor Strange might return, why he gets the Third Eye, and what the future looks like are some of the things explained in the ending. The balance in the multiverse has been destroyed by his dream-walking across the multiverse. It would make sense for her to join the Young Avenger team in live-action. If the MCU creates the team in the future, America could join it.
Doctor Strange will return at the end of Doctor Strange in the Multiverse of Madness. The future of the shared universe and Doctor Strange's story could be impacted by the addition of Clea. The rest of the Fantastic Four, as well as Professor X and members of the X-Men, could be seen by fans. With Wanda gone and the multiverse not under threat of destruction for the time being, Doctor Strange 2's mid-credits scene shows him pulled into another adventure with a mysterious woman who knows exactly who he is.
The mid-credits scene is one of the biggest surprises of Doctor Strange. The introduction of incursions points to a big event happening within the multiverse when the boundary between two universes collide. Doctor Strange is taken with the sorceress, Clea, to fix what he messed up. The Eye of Agamotto is a talisman that is meant to show whoever wields it the truth. Realizing she doesn't want to be the terror she sees on her kids' faces, and knowing they are well-loved by Earth-838's version of herself, Scarlet Witch backs off and works to make things right. Saving the multiverse as a whole could bring every superhero back together after an incursion.