From the teaser it looks more likely that Venom will be a villain introducted in #3 and leads into #4. The teaser plays it up like the movie is mostly about the internal conflict that the black costume causes in Parker. And plus we saw a lot of sceens at the church when Parker tries to get rid of the suit and then we see Topher Grace/Brook seeing Parker. It is because of that I think that the church sceen would make more sense at the end of the movie. So these few sceens lead me to beleive that the rumors of Venom showing up for 15 minutes then dieing are very unlikly. Atleast I hope their not true.