Can "The Vampire Diaries" really go on without all three of its main characters?

E! Online reported that out of the series' three main characters - Nina Dobrev, Ian Somerhalder and Paul Wesley - only one has not yet signed on for season seven. The site did not mention which star is having doubts.

Despite the decrease in ratings, sources confirmed that a seventh season is highly possible. During Comic Con executive producer Julie Plec told E! Online that the "show will go as long as the actors want the show to go."

Everybody's under contract," Plec said. "I know that we've got plans for season six, we've got plans for season seven. I know that our bosses have plans for seasons eight, nine, and 10. I said I want to be part of it as long as I know I could keep telling good stories and as long as the ensemble people that I work with want to be there and are committed and dedicated. So, so far so good, you know."

Adding: "We'll see how long we can stay, doing it well. We'll make sure that we don't start sucking."

E! Online reported that there is a possibility that the series can move forward without Dobrev, Somerhalder and Wesley. Season five of the show ended with a major cliff hanger, since Damon and Bonnie are considered dead.

"You'll see enough of them to make you happy and more as it goes along," Plec told E! News. "They are by no means going to be off the air for six episodes. The mystery is where are they, what happened, are they dead, not dead, and what the hell are they going to do together, those two of all people?"

"The Vampire Diaries" returns Thursday, Oct. 2, on the CW.