Yeah, I mean, it could have worked. Maybe fudge the details so he was involved in abducting Alice as well, to cover Wonderland story. Go through the whole "turning on Sora" in Traverse Town; and have a convo with Hades in Olympus. The only ones that would need some embellishing would just be Atlantica and Halloween Town.
Very late post, but I agree. He could've reflected on his power-tripping at Traverse Town, that his relationship to Sora was always built on him being the one they could depend on and Sora becoming strong sort of displaced his role in their relationship to one another. And you're right, they could've easily come up with a brief Key of Beginnings scene for the worlds he played no role in, too. I always thought Atlantica would be the Disney world that would most remind Sora of Destiny Islands of the worlds he visits in 1 and 2--from the land side of it, anyway. Same thing for Riku. Riku could observe something along the lines of how far away and unreachable the sun looks from the bottom of the ocean (the light being what Ariel reaches out to touch in POYW), and reflect on how he had always looked out from the land to the ocean instead. Riku was Moana
before Moana, lol.
And I know this one couldn't have happened, but looking backwards: Maybe in Halloween Town (seeing a holiday like Halloween made "real"), he thinks about what he said to Sora about Santa Claus in the past. IDK though, Nomura and Square were working on KH2 at the same time as CoM, right? So perhaps not impossible.