Chris Hemsworth reveals he turned down Star Trek 4 because he wasn't satisfied with the script. A couple years prior to his big breakout as Thor in the Marvel Cinematic Universe, Hemsworth had a small, but memorable, role in J.J. Abrams' 2009 Star Trek reboot. In the opening sequence, the actor portrayed George Kirk, father of James T. Kirk, who heroically sacrificed himself so the crew of the U.S.S. Kelvin could get away to safety. George's death loomed large over Jim over the course of the new films (particularly the first one), as Jim looked to live up to his father's legacy while becoming his own leader in Starfleet.
This personal conflict would have been at the forefront of a planned fourth installment, which was initially announced in 2016 (shortly before Star Trek Beyond opened). One of the few plot details announced at the time was that the movie would see Hemsworth - now a bona fide star - return as George to co-lead the film with Chris Pine's Jim. Unfortunately, Star Trek 4 never came into fruition, and Paramount pulled the plug on the project earlier this year. Now, Hemsworth explains why he didn't sign on.
Speaking with Variety, Hemsworth stated he wasn't intrigued by the script and felt it wasn't strong enough to warrant George's comeback:
"I didn’t feel like we landed on a reason to revisit that yet. I didn’t want to be underwhelmed by what I was going to bring to the table."
There's no denying that it would have been a lot of fun to see the two Chrises play off each other (imagine Indiana Jones and the Last Crusade if Indy and Henry were both in their primes). However, it would have been extremely disappointing if the actual film didn't live up to the on-paper potential of the premise. Based on Hemsworth's quote, it sounds like the creative team hadn't really cracked the narrative at that stage in development, causing the actor to have doubts about the film. Bringing George back was a bold choice - not only would Star Trek 4 have to be highly entertaining on its own merits, it would run the risk of undermining the emotional component of the first film's cold open. Hemsworth decided it was better to leave that untouched unless there was a compelling angle to explore.
Star Trek 4 was moving along in development before it was shelved, with S.J. Clarkson calling the shots and the principal cast from the earlier films ready to reprise their roles. It'll be interesting to see if it ever starts back up, but the odds of that happening are low right now. Star Trek Beyond underperformed at the box office, earning just $343.4 million worldwide against an $185 million production budget, so there clearly isn't much audience interest in the continuing stories of the Kelvin Timeline. Maybe Quentin Tarantino's in-development Star Trek film will give the franchise the shot in the arm it needs. One thing's for sure, Paramount won't let one of their prized possessions remain dormant forever.