He's successful at a near-surreal level, taking enormous risks and earning all the "F you" money he's gotten in his career. Supposedly he's calmed down as a person, too, which is probably good for both his health and his colleagues' sanity. I've always liked his work, and sometimes I've loved it. And I'm thinking again about 2009's Avatar, soon to be dethroned as highest-grossing American film by Star Wars: The Force Awakens. I love that it will take a Star Wars to beat it.
(Quick aside: I like Avatar; I literally wobbled as I left the theater, and briefly forgot to remove my 3-D glasses. Avatar is an odd piece of pop culture, though, where lots of people don't revisit it and in fact seem to have trouble remembering it, problems Cameron's Titanic -- which I loved -- has never had. This entry has nothing to do with that, but I felt I should acknowledge it, in case someone's all "Huh? Why are you bringing up that?")
Cameron and co-writers are working on sequels (yes, plural) to Avatar, which I hope are amazing; but one facet of the original Avatar can't really be replicated, and that's the score by the late James Horner. First off, Cameron lost not just a colleague when Horner died in a plane crash last summer, he lost a friend. That friendship was hard-won, and nearly torpedoed by how tough an experience 1986's Aliens was; Horner vowed he'd never work with Cameron again after that. Even with that bad experience and years apart, Horner let himself be moved by just Cameron's Titanic script (he reportedly cried while reading it and said it was the film he was "born" to score) -- and Cameron had let himself be moved by Horner's music for 1995's Braveheart. At some level, Cameron was thinking This is why I like him. They tiptoed back into each others' lives, and found the rhythm of working together again. (To the point that Horner felt OK about explicitly going against Cameron's injunction not to write a song for the film, and wrote and demo'ed "My Heart Will Go On" in secret, feeling -- correctly -- that the strength of the song would change Cameron's mind.)
In other words, how do you replace a friend?
There are more nuts-and-bolts reasons the music question is a delicate one: as hugely popular as Horner was...who else in the current film score world even kind of sounds like him? Is similarly long-form (Horner often wrote 10-minute-plus music cues, a lonnnnnnng time in films)? Would be willing to make a time commitment like what Horner made to the first Avatar, which he spent a year-and-a-half scoring? Would know how to navigate around the James Horner-sized hole in James Cameron's life? Maybe composer and noted nice guy Alan Silvestri, who worked with Cameron before on The Abyss (1989), could commit to this and adapt his sound to connect to -- not copy -- what Horner did, but I have no idea how his working relationship with Cameron went. Howard Shore has shown willingness to spend years on giant overarching projects, both The Lord of the Rings and The Hobbit, but I don't know if he'd want to make another, similar commitment to someone who's not Peter Jackson or David Cronenberg.
It's not going to be Danny Elfman (probably wouldn't get along with Cameron). It's not going to be Hans Zimmer (music style likely too divergent). It's not going to be Brad Fiedel, even though he's worked with Cameron three times (his music's too stark and monochromatic). Mmmmmaybe it could be Bear McCreary, except he's busy with all sorts of TV shows. Michael Giacchino is much more from the John Williams school than I think Cameron would want. But I also didn't think Thomas Newman was the best choice for James Bond, and he's done good, lush work in that series. Twice. I'm unfamiliar with too many of the current crop of younger film composers to know if any of them come near to being a potentially good fit, and there's still a risk to someone young if they go off the market too long.
Like in any relationship, James Cameron needs to find someone who fits, and he needs to give that person room to fit. And to fit even when there's the chance for an elephant in the room, in the form of the missing relationship.
If even I am thinking about this, imagine how Cameron's thinking about it.