There are rumors about the potential return of Josh Brolin as Thanos in an upcoming Avengers film, with some outlets suggesting it could be in 'Avengers: Secret Wars' and others mentioning 'Avengers: Doomsday'. The possibility of Brolin reprising his role as Thanos has been discussed, but it is unclear which film he might appear in. The details of the upcoming Avengers films, including their titles and plots, appear to be uncertain and subject to speculation.