After appearing in all three previous installments in the franchise, Arnold Schwarzenegger opens up about why he’s not returning for The Expendables 4. The first Expendables was a surprise hit in 2010, earning over $274M at the box office. Schwarzenegger had a brief cameo in the movie as Trench Mauser, and he would return for both sequels in a supporting capacity. Director Scott Waugh's upcoming fourth film is set to see the return of stars like Sylvester Stallone, Dolph Lundgren, and Jason Statham, but Schwarzenegger will not be reprising his role.

https://screenrant.com/the-expendables-4-movie-cast-arnold-schwarzenegger-response/