Another Side, Another Story and Deep Dive are valid. Just because they're old, doesn't mean they're not accurate. And no, it wasn't their "idea" of Kingdom Hearts II, it was just a teaser for the game to get people to think and to keep them interested in the series. While the scene that actually takes place during the teasers won't happen, the information, for the most part, appears to be correct. The teasers also aren't just for Kingdom Hearts II, but anything beyond the end of Kingdom Hearts. Chain of Memories, for example, had some of the information from Deep Dive within it -- most notably the scene with Sora standing at the crossroads..:KL:. said:
Okay.....One thing is that ASAS and Deep Dive is NOT valid. It's been 3 or more years since they made it. That was just their idea of KH2 not the actual. Plus ideas change and they werent making KH2 when they made that. No blindfolded Riku, no BHK in a cloak, no Kairi that looks like that, no GEU, no advanced town thats in the dark, no dark beach. Now if it was still valid we would have seen these already in at least some screen shot or trailer. Same goes for the 13 points. Nothing you have can back it up. So move on and forget it. And unless you have some proof that they are still using it besides Mickey and Riku in a coat then go ahead and prove me wrong.
Oh, and for the record, GEU and SU do exist. They weren't just shown during Deep Dive, they were also shown turing the TGS 2003 trailer. (AKA the "Tech TV Trailer.") The scene was also taken straight from Deep Dive, hence they're still using it (or were at that time), and it's still accurate/valid. As for "Blindfolded Riku," most still assume that was a cheap ploy to leave "some" doubt as to who he was -- same goes for them not showing Kairi's face. BHK/DWU could be for a similar reason since they didn't seem to want to show his face, or he could have become a "Shell" during the course of Kingdom Hearts II. Also, the game doesn't even have a real release date yet -- there's a large amount of information that they haven't (and likely won't) revealed.