I was about to entitle the topic "Your Movie 14" but since it's coming, why not wait for a year and a half for people to share their ideas on possibilities that will be revealed in Movie 15.
--- I'll start with mine. (I don't exactly plan to 'post' it out as a story; just ideas or so.)
Like movie 13, they made a "pattern" of the movie. A case related to the Black Organization case which can be split into two: the kidnap and impersonation, and the Black Organization, themselves. I'm thinking of movie 15 to be somewhat like this but not exactly.
They would start the intro of Conan being cornered by the Black Organization, suddenly start the movie opening theme, proceed with a flashback-like story and in the middle of the story, they show Conan being cornered by the Black Organization as in the shown intro. So here are the possible patterns that I'm hoping to come out. (Although these aren't very original, creative, or idealistic, I kind of like these kinds of thrilling stories.)
Intro - Conan is cornered by the Black Organization
Flashback-like of what happened before he was cornered which Ran appears to be suspicious of Conan again of his boyfriend-like actions. Conan notices and tries hard to persuade Ran that he isn't that kind of person before Ran reaches the conclusion that he is Shinichi. Something fortunate happens that allows Conan to be excused for a while like an urgent case allowing him to think of an idea to make an excuse. The case was easy for Conan so he immediately solves it by using Kogorou to solve it, as usual. As Ai disguises herself as Conan, Conan takes the prototype drug that Ai made but he noticed that it only can last for 30 minutes. He uses the same trick but an unfortunate thing happens...
Vermouth witnessed it with her very own eyes her transformation back to Conan coincidentally. (You know what happens next.)
Basically, it's a combination of a random case + (near to) revealing the true identity of Conan + the Black Organization case. Although it would be great if they make a twist about Kaitou Kid but I think it would somewhat mess up the idea of the author (not that much, though) and the director. It's kind of a hassle but it would be great and at the same time, a big thumbs down since people might think "The movie has gone crap: trying hard to fit everything in a single movie."
That's just my made-up story so if you could share yours, it would be great. This is just for fun, anyways. xD