In all honesty, it's somewhat surprising that Pacific Rim 2 is even happening.
The first film wasn't perfect, but it was a fun, action-packed kaiju slugfest with a lovable cast of characters and some absolutely gorgeous visuals - that being said, it wasn't the critical reception that almost killed the series. To put it lightly, the film was a huge bomb in the United States, making only a fraction of its budget back during its theatrical run. In fact, the only reason that a Pacific Rim sequel is in production at all is because the movie was a huge hit over in China.
Thankfully, Legendary Pictures took over production of the sequel and things finally started moving forward. Not only that, but Star Wars: The Force Awakens star John Boyega was signed on as the film's lead - for fans, Pacific Rim 2 went from "fever dream" to "dream come true."
However, the addition of John Boyega seemed to hint at some major changes to the cast of Pacific Rim. If Boyega is going to take over as the film's main character, what role will Charlie Hunnam play? As the protagonist of the first film, many expected Hunnam to return in some capacity, but as it turns out, that's probably not going to happen.
In an interview with MTV, Charlie Hunnam - who played Raleigh Becket in the original Pacific Rim - said he will not be returning for the sequel. At the very least, it's not because of creative differences or contract disputes, but scheduling conflicts:
"There was definitely an incarnation of this sequel that involved me, but there was a changing of ownership, of the studio itself, Legendary, and I think that because they partnered up with a Chinese company ... there was a real agenda to get that film into production as soon as possible, and I was already booked up for a significant period of the time they were going to need."
Considering the fact that Pacific Rim 2 was in such dire straits for such a long time, it's not all that surprising that Hunnam signed on to other projects. For a long while, no one seemed to know if the movie would even happen - the fact that Hunnam was looking for work elsewhere makes a lot more sense than keeping a clear schedule for a movie that almost fell apart.
Hopefully, Hunnam's other commitments don't completely prevent him from appearing in the film altogether - but, given just how many different projects Hunnam is set to star in, there's really no way of knowing one way or the other.
At the very least, Pacific Rim 2 is still happening: the film is due out in early 2018.
