I think several things would have to be done with the Breaking Dawn film in order to make it work. Firs off, it would have to be done as two movies, something which Summit is already considering. It would be needed to cover the entire scope of the book, which should have been two books anyway. I think an R rating, which I'm aware SM won't go for, is absolutely necessary in order to truly capture the intensity of the book. Also, I think they need to smooth out the Jacob/Renesmee relationship, and make it seem less pedophilic than it comes across in the book. Finally, they should actually have Cullen and friends actually battle with the Volturi Guard, in the movie as that was the major let down of the book for me. They should do something like Andrew Adamson did with Prince Caspian, and have the Cullens and their allies try to avoid the battle but end up fighting anyways due to some treachery on one side or the other. This would remedy all those easy outs that SM took when writing Breaking Dawn, as well as make it seem like less of an anticlimax than the book did.