This is a rumor regarding RoF that I haven't seen discussed yet:
So supposedly, in one scene during the climax of the film, Sorbet (the dude that took control of Freezer's Planet Trade Organization after his death), after witnessing Freeza's defeat, says to himself "everything is going according to plan.." and disappears. I don't know if this is 100% true, but if it is, why would Sorbet go on a quest to revive Freeza, if he just intended for him to get killed again? What greater purpose does this serve? If he does indeed say that, then it's an obvious hint that Toriyama & co. have plans for something bigger that will happen in the next movie. As far as I know, and from what I've read from those that have watched it already, there are no other hints or clues in the film that shows "what happens next," other than this little tidbit.
Once again, until the movie is released or leaked early, take this with a grain of salt.
Once again, until the movie is released or leaked early, take this with a grain of salt.