Finally some good news for this film! Black kept talking about scale but after losing Del Toro it's been pretty depressing. Holbrook might be a good actor but he's not a leading man. Key is funny but in a Predator movie? Let's see. Olivia Munn? Neither a serious actor, action star or comedian.
We don't live in a time of movie stars who can open movies but you still have your "hot" list like The Rock, Statham, all the Chris's, Tom Hardy, Fassbender, Cumberbatch, etc. Black had RDJ and Kilmer, RDJ again then recently Crowe and Gosling so he's used to having strong personalities leading the film.
Jane never got the career he should have but he's always good to see in a flick, particularly one with action. Someone mentioned Game of Thrones actors but their list of duds is endless, Conan the Barbarian, God's of Egypt, Terminator Gen, etc.