The original release campaign
Disney's August 19, 2021 trailer announcement described Eternals as an ensemble of heroes who had long protected Earth and must reunite when the Deviants return. Chloé Zhao directed the film, with Gemma Chan as Sersi, Richard Madden as Ikaris, Salma Hayek as Ajak and Angelina Jolie as Thena among the cast.
The announcement set a November 5 theatrical release. Final trailer meant a stage of the promotional campaign; it did not mean the final film Marvel would make or the last possible appearance of its characters.
Source [1]What a trailer leaves unanswered
A trailer selects images and dialogue to establish a premise. It is not a complete scene-by-scene account and should not be treated as confirmation of every fan theory. Readers who want the separate Eros credits-scene explanation can follow the related Harry Styles article, which includes a spoiler notice. This page preserves the trailer's date and team introduction without presenting the 2021 preview as a new release today.
Source [1]