The Lord of the Rings: The Hunt for Gollum is bringing back Andy Serkis (who also directs) as Gollum and Sméagol, Ian McKellan as Gandalf, Elijah Wood as Frodo Baggins, and Lee Pace as Thranduil. And while Aragorn, aka Strider, is also part of the story, fans learned earlier this month that Jamie Dornan would be taking over the role in place of Viggo Mortensen , who played the character in Peter Jackson’s Lord of the Rings movies. Mortensen hasn’t gone on the record explaining his decision not to return, and Serkis coughed up precious few details about his film’s casting while talking to Josh Horowitz on the Happy Sad Confused podcast (via Entertainment Weekly ). “I really, really don’t want to go into it right now because I do want to save that for further down the line. I’m going to save all discussion about casting,” Serkis said; presumably, that means we’ll be learning more about Mortensen’s decision not to return eventually, maybe when the movie is closer to release.…