Well, because Marvel tells us so.
Marvel executive editor Tom Brevoort made it crystal clear: “A core character from the series, whom you've seen in the [2005 and 2007] films, will be no more,” he told CNN.Yeah, right. If it lasts a year I’ll be totally surprised, but you are hearing it here, if not first, and least first from me, it wont last. Let me make this prediction, whoever it is that dies, will be back sometime before the next Movie or TV appearance of the FF, because we all know that Marvel allows the tail to wag the dog.
My pal, sometimes writing partner, and huge FF fan John Wilcox likes to remark that Stan Lee has been the only writer that has been able to consistently keep the team together (100+ issues, as I recall). Now that's what I consider to be an interesting story.
And now, for something completely different...