Not for the rumour camp - James Earl Jones has confirmed that we will all hear his terrifying tones in the third prequel:
From scifiwire
From scifiwire
Jones Back As Vader
James Earl Jones told the Toronto Sun that he will reprise the voice of Darth Vader in the upcoming third Star Wars prequel, Episode III, in 2005. Director "George Lucas says, 'When Anakin goes bionic—that will be in the last five minutes of Episode III—they will hear you."
Jones also expressed approval of Hayden Christensen, who played Anakin Skywalker in Star Wars: Episode II—Attack of the Clones. "Aren't you impressed with him?" Jones asked the newspaper. "I like his whole bearing, the spine, the neck. ... He's like a snake."