We learn in the movies Doctor Strange (2016) and Avengers: Infinity War (2018) that all sorcerers including Doctor Strange have sworn an oath to protect the Time Stone at any cost. But in the concluding scenes of Avengers: Endgame (2019), Captain America returns all the Stones in their past, which means Doctor Strange and Sanctum Sanctorum in the present do not possess the Time Stone anymore; so what will they be protecting now?
Given the importance of Time Stone, will Doctor Strange no longer need it to fight enemies unknown? Doctor Strange used it to defeat Dormammu which would have been very difficult without the Time Stone.