Why do people think Caroline?

Julie confirmed that Silas will be in S5.

I don't think anyone will die. Maybe the one who takes the cure dies for a bit and then he/she wakes up. But if anyone dies maybe is Bonnie....

it's not gonna be silas he probably the villian for season 5

I haven't read any interviews, but I think Matt dying could make sense. That would be a reason for Rebekah to leave Mystic Falls after all and join her brothers. So, as she is going to be on The Originals show... And Matt dying might also stir Elena's emotions again. Those are only quite random speculations though.

Just don't kill off my Katherine!!! She's the one I'm most afraid about. My other favorites are rather unlikely to be killed off, I think.