Speed

We won't know for sure until KH3, but a popular guess is that Xehanort had taken complete control of Terra's body and that it melded to who was in control of it.

I feel like Terra would be the one who helps them from the darkness, if he isn't saved before the war. Vanitas seems too robotic to rebel against Xehanort. The only time he really disobeyed any orders was when he tried to barbeque Ventus.

Okay, Riku saw Mr. Robe guy at the beginning of the MoM exam. Because of this, he sensed something was wrong, so he unknowingly dove into Sora's dreams and became a Dream Eater. While Sora was traveling through the dreams of each world, Riku was traveling through Sora's dreams of each dream world (inception much?). Since Riku was in Sora's dreams, we can guess that Riku being awake forces Sora to fall asleep so that Riku has a dream to be in and vice verca.

That dull, ordinary boy -Xehanort

With all of the foreshadowing and plans being revealed, there doesn't seem to be many reasons to acually go to any of them. We might have to fight the new Organization XIII in different worlds, but that sort of contradicts the whole Keyblade War concept. The heartless and/or nobodies might cause mischief, but there isn't much reason for them to do so. Maybe they'll make us revisit old worlds when we rescue Ven at Castle Oblivion. How do you think they will incorporate Disney worlds into KHIII?

Then the series would end with Kairi finding Sora "snoozing" down on the beach like in KH1.

I'm sure she'll get some spotlight in KH3. They might put her as the prologue character like they did with Roxas in KH2. It would make sense with her training and everything.

Plot-convenient stupidity from the main characters.

He said that he had Sora and Terra. The third one is the unknown, strongly hinted to be Kairi, 7th Guardian.

Being possessed by a Xehanort's Heartless doesn't qualify as becoming a Heartless. He shouldn't have a Nobody.

KH2 and BBS were both pretty epic.

I liked flowmotion and the bigger maps, but the worlds felt generally empty. IMO, the game would have been much better if there were more NPCs to talk to.

I'm a rat, so Xemnas. Fear my nothingness!

BBS. The story was more interesting and suspenseful.