These are all very good points. On the aspect of romance, it's nice to see someone resolve a romance subplot without waiting until the very end, so we can actually
see the relationship in progress. So many series will end with two characters, major or minor, finally agreeing to give dating a shot. This is a refreshing change of pace, and may be part of why Gosho is advancing some of them so much. However, if you look at Shin/Ran and Kazuha/Heiji, you'll see their development isn't at that point yet. Conan/Shinichi has obvious restrictions that prevent him and Ran from advancing their relationship too much, but as the main characters of such a long story, it's not too strange they would confess their feelings more in the middle. It adds to the tension between Conan and Ran. Kazuha and Heiji, though, are almost always together and yet have made very
little progress. They'll probably be one of the biggest "end-is-near" warning flags. ^_^
Ran's suspicions seem like they're well-founded. Of course, it could also just be fans of a long-running series looking for a single sign of plot advancement. If you're desperate enough, you'll take what you can get. Of course, with Detective Conan, those little hints can often prove to be correct, so there's that. I think at this point, though, Ran probably understands that there's something bigger going on; I mean, he's suddenly a little kid. There's not many explanations aside from magic. And he's made such a big deal of hiding it, it's clear he's not just doing it to get close to her. After all, they were already pretty close to begin with.
As for where the arc will go from here... I actually had a dream that Amuro was killed in a flood, and I thought to myself, "That's probably the only way to end his appearance without Conan being found out by the BO." However, I can't help but wonder if there are other ways and paths this arc can take. We're all focused on his investigation into Conan, but it could easily be a red herring for the readers as to how the arc will conclude. I mean, sure, he knows where Agasa lives now, but Subaru Okiya (or as I like to call him, Shubaru Akaiya) lives
right next door. From what I've seen, he seems more interested in getting Akai than anything else. Honestly? I think he'd be willing to betray the organization to pursue Akai. This arc could easily go one of three ways:
1) It will be a straightforward development: he'll discover the truth about Conan, maybe about Ai, leading to a huge showdown with Vermouth probably thrown into the mix.
2) He will be derailed from his investigation into Conan by the discovery of some sort of definitive proof that Akai is, indeed, alive and end with a big showdown between them, possibly with Sera thrown into the fray. Of course Conan will be involved somehow, being the title character and all.
3) A combination of the other two, which is, honestly, the most likely scenario.
We can't be sure how Bourbon's appearance will end. Since Vermouth is concerned about Conan and Ran, she might end up shooting him if he finds out the truth. I can see Conan or Ran trying to help him as he dies, possibly revealing Conan's identity if it's the latter. Then he could be buried by his good friend, Officer Takagi the First.
Well, to wrap this up, on the note of the end being near... Well, with my luck, it wouldn't surprise me. I tend to get into a manga series literally right before they end. Seriously, it's happened so many times I might as well advertise myself as the Harbinger of the End.
I'm pretty relieved to find an ongoing series that doesn't end one to six months after picking it up. But right now, I don't see too many signs pointing at a quickly impending end to the series. However, I do see a couple leading to the end of this particular arc... I think Gosho WILL wrap the series up within the next two or three years, though.
