Re: Jimmy/Jenny - where do you stand?
Maybe she dies and Jimmy will take her place in the sequels.
I don't see Clark, Lois, Perry, Martha dying here. Maybe they thought the movie needed an emotional death besides the death of Jonathan which seems pretty much a given now. So Jenny is created for this purpose alone, that's why she got screen time in trailers, she could be a cute and charismatic minor character that will have enough screentime to makes us care for her death.
"A 12 year old Ben Linus brought me a chicken salad sandwich. How do you think I'm doing?"