First off, i've got to thank you for posting the chart again. For some reason, the second line under endless in VII has been illegible in every form of the chart I've ever seen. Finally someone posts it!!!
Moving on, I like the conclusions that you listed regarding the BHK. I think that he's one of the reasons why I want to play KH2 so bad, just to see what his deal is. I've read and thought about so many of the possibilites that it hurts. Here are some of the things:
1) His appearance- Since we have pictures of his face to compare to people now, and even before we did, the common consensus seemed to be that BHK looked near exactly like Sora. And in ways this is true. This has spawned the ever popular "other-side-of-Sora's-heart" theory. While I agree that there is some connection between Sora and BHK, I doubt that they are each other's yin and yang in the terms of light, twilight, darkness, whatever. And the is no way in hell that they're brothers! No way. The most of Sora's family we ever get is his mother yelling at him that dinner is ready. I think that whatever BHK's deal is, its going to be something that is going to make us go "Wait, this makes sense. This thing and that thing are related to it, and it explains this and that." Its going to make things click, not confuse us or be something way out of right field. I also love all these names people keep coming up with (take note of the sarcasm here) too. I mean for the love of God, TYKE??? I know how it happened too, because someone on the board who claimed this way back when had a linked site. The site used the term tyke to DESCRIBE BHK. It wasn't even in caps!!!! It amazes me that people can be that unintelligent. There have been others too, of course, many of them idiotically America. Look at the names of the characters (Disney doesn't count): Sora, Riku, Kairi (all Japanese), Ansem, Namine (not ur common everyday American name). Then soem brilliant person tried to say his name was Jack Twilight or something. First of all, WHAT THE HELL IS WITH THE LAST NAME??? No other character in the game has a last name, why is he going to? Especially TWILIGHT!! Wow, I just realized I really got off of the 'appearance' topic.... Sorry! Um... so yeah, thats pretty much how I feel about his Sora connection and the whole name fiasco.
2) Connection to Namine- Another thing we have seen is BHK in what I assume to be Castle Oblivion talking to BHK. To me, they also seem to look alike. I'm not going to hop on the "BHK and Namine are related" bandwagon that some have, but its plausible. This, however, could explain why BHK (as DWU in ASAS and DD also, since they aren't really one and the same, DWU set the stage for BHK) was looking for/ is defending Sora. This was just an idea- I dont necessarily have proof, but here it is-
Sora emerges from the memory pod thing in Castle Oblivion. I immedietly thought if the last line in DD, which is "Everything is coming back to me, the true..." which I always believed would end with "... memories." Maybe he ran off to do something rash or maybe something went wrong in restoring his memories, and Namine knows it but doesn't know what to do or doesn't have the power to do it. So, she recruits BHK, either because she knows him or because he's connected to Sora or whatever your belief is. BHK then goes to help Sora. Its a possibility.
I'll stop rambling about BHK for now, tho I'm sure many of us could go on for hours.
Anyway, my opinion on the dead members of the Organization. Of the ones that died, the only one I could see coming back in 2 is Marluxia. However, I'm suspicious regarding Zexion's death. Unlike every other member of the Organization, we didn't see Zexion fade into nothing. All we see is Repliku (thats what a friend of mine and I call Replica Riku) advancing and the screen goes black. So it could be that Zexion comes back, which I think would be cool.
I really don't think Riku and Mickey have 'joined' the Organization. We know that they study aspects of the heart, so maybe they're there to gather information in that respect. Another possibility could be that Riku and Mickey are still in contact with DiZ, and they may be helping him or vice versa. However, we still aren't completely sure if DiZ is good or evil. No matter what tho, I believe that he is somehow part of or connected to Ansem. The phrase in the 13 Points chart "A creation born of ignorance" comes to mind. Of course, Riku and Mickey could have absolutely no connection to the organization at all. Maybe Riku and Mickey, at the end of CoM, decided to shower at Castle Oblivion to get all the darkness buildup off of em and they were going to wash their clothes. However, the washer was broken, so they stole some of the Organizations robes and left. ;-)
The last thing I would like to comment on was sparked by excalligrapher's sig, the pic of Namine and Kairi. They look oddly alike, don't they? In CoM, I didn't take Namine's explination of her being Kairi's "shadow" as that Namine was like the other side of Kairi's heart or anything. And I still don't. However, I think they're could be a connection between the two. What do you think?
O, ok sorry, one more thing, something that I remembered because my little brother wanted to watch me play the ending of KH1 again the other day: During the end CG sequence, when Destinly Islands is being revived, one of the little balls of light coming from the sky floats down into Kairi's hand and there is a brief music pause and complete silence. Does anything think that this could be something of importance later on? I couldn't think of anything plausible that it could be that really made sense, but its one of those things that keeps grabbing my attention.