The Facts: The next movie is set to feature Amuro. The Movie 21 teaser was seven-segment electronic display counting down from 5 with a metropolis in the background, and Amuro spoke the final countdown number Zero, a reference to the PSB.
My Speculation: We will see the logical followup of the anime/movie introduced character development from Movie 20 that Rei Furuya knew Matsuda Jinpei from police academy, and learned bomb defusal from him. Someone who likes setting bombs with mysterious clues is gonna go nuts, most likely in Tokyo since that is PSB territory, and Conan, Amuro, and whatever characters of the day are being served will go put a stop it. The seven-segment display countdown is a reference to a bomb countdown display like most DC bombs use. If this is the case, I'd expect new character Hyoue Kuroda to take a front-seat role in the movie replacing Matsumoto as the shouty police pusher..