Resident MCU loudmouth Frank Grillo made a splash a couple of days ago in the news cycle when he confirmed that his character Crossbones was returning in an Avengers 4 flashback. A producer on Avengers 4, who happens to share a surname with Grillo, was at the Austin Film Festival talking about the hardships working on a film as huge as this and casually mentioned they filmed with Tilda Swinton for a day. As per SuperBroMovies:
Michael Grillo revealed this during a discussion about the crazy hard experience filming and prepping Avengers 4, saying: “when we got Tilda Swinton, she was just a 1-day availability.”
Looks like the Ancient One will be one of the many departed characters making a return in the film. There’s been a ton of reports and rumors suggesting time-travel as a main plot element as well as the inclusion of Tony Stark’s B.A.R.F. technology. The Ancient One has obvious ties to the Time Stone, the stone that allowed Thanos to execute the final step of his plan when he reversed Vision’s death at the hands of Wanda. It makes sense for her to be one of the characters returning.