According to The Hollywood Reporter, Star Trek 4 might have just lost its Captain and his dad with the studio failing to reach contract terms with Chris Pine, and Chris Hemsworth.  

Shortly before Star Trek Beyond beamed into cinemas back in 2016, J.J Abrams announced that Hemsworth would be returning as Kirk's father in a time-travel themed sequel. A pre-Thor Hemsworth made a brief appearance in the first of Abrams' rebooted Star Treks as Kirk's doomed father. However, the tentative plans to fast-track a sequel got served a curveball after Beyond could only muster $343 millionworldwide. Ranking as the lowest grossing in the franchise (yet the most fun), Beyond had a hefty $190 million production budget, and the future of the big screen exploits of the Enterprise was in doubt.

Both Pine and Hemsworth already had preexisting deals with Paramount and Skydance, but as Star Trek Beyond didn't turn much (if any) of a profit, the studio is renegotiating in a bid to keep the budget as reasonable as possible. I'm still unsure why Beyond didn't at least match the $460 million-plus haul of Into Darkness, but I'm sure those sloppy trailers that sorely missold the movie didn't help matters.

Star Trek is an important franchise for Paramount, it may not have the global appeal of Star Wars, but its fans are no less loyal. Paramount's new CEO Jim Gianopulos has been vocal of his desire to build on the franchise. Thanks to the successes of A Quiet Place, Mission Impossible Fallout, and the potential blockbuster in waiting in the form of Bumblebee, Paramount is having one heck of a year.

At this stage, Pine and Hemsworth shouldn't be ruled out as they may yet come to agreeable terms with the studio. Other cast members including  Zoe Saldana, Zachary Quinto, Karl Urban, Simon Pegg and John Cho are all expected to return, but the future of this incarnation of Star Trek is currently in doubt once again.