I think the boss is someone we wouldn't expect. I do not think it is James Black, because that is something we would expect. I think it would be someone, that when found out, would bewilder the audience. I'm talking like a Detective Boy, Dr. Agasa, Inspector Megure, or Yoko Okino, and that's a limited list. I doubt when the ending does air, it's going to be a short arc, like the one with getting Kir out of the hospital. I think it would be one with 50-60 episodes, maybe more, maybe less, but definetly more than ten. The following things I believe would happen:
1. Shinichi has a showdown with the men who shrunk him, and Anokata.
2. Kazuha and Ran would somehow be involved.
3. Kaito Kid may be chasing the same organization.
4. Ai gets killed, or she will forever remain as Ai Haibara.
5. Shinichi and Ran get together.
6. Heiji and Kazuha get together.
7. The Detective Boys sneak into the hideout.
8. There will be a huge, tension-filled scene where Shinichi tells Ran he was Conan the whole time.
9. Like Episode 345, there will be a lot of twists.
10. Shuichi Akai, if he hadn't already, comes back.
11. Kogoro is mad at Shinichi for using him. He does, however, get back together with Eri.
12. Some people will probably die.