I actually had a dream the night before Princess Diana and Dodi died. I was living in the UK at the time. It was a Saturday night, into Sunday morning. I woke up early on Sunday and told me ex-husband at the time that I felt really heavy and sad...that I had a dream that a blonde haired woman and a dark haired man were dead..in a bathtub. It was a horrific scene.
My young son came into the room, so I went downstairs to make him breakfast. I turned the Cartoon Network on for him and a buzzing message came through to to turn to a news station. They had announced the death of Diana and Dodi. My ex-husband gave me that you're probably crazy look.
So I do believe that you can have dreams that turn out to be reality. I've had several since then, although none as huge as the Diana dream.