I like the idea of having Xehanort's memories somehow interact intrinsically with the Realm of Sleep (I don't think they construct the RoS, however) because it would enforce the notion that Xehanort has been influencing the plot of KH actively since he started traveling through the Worlds. The more justification we have for Xehanort's involvement in events, the better, since we essentially only see him in BBS as a needlessly (if delightfully) evil character with no apparent motivation for his actions. This could work both if the MF is actually Xehanort, obviously, or if the MF is simply a shape shifter taking on different forms of Xehanort based on his memories. Perhaps the MF is a being of pure memories, sort of like Xion.
I would also enjoy seeing Kairi's role in the story expanded. Your theory is proof that it could be if Nomura and team would be a bit more creative with her; I doubt we're going to see it happen with this game, but who knows? It's possible, depending on the ending of DDD, that she could play a pivotal role along the lines of what you're suggesting in another installment we receive prior to KH3. If they were to incorporate her into DDD in a R/R type scenario, I think it would be cool if she actually fought alongside Namine, somehow. That way, perhaps they could maintain some consistency with switching between characters even in the Realm of Light, since they're inhabiting the same Body; we could switch between Namine and Kairi, each have certain abilities which are practical or necessary for varying developments, and they would follow the same plotting unlike Sora and Riku, so they wouldn't have to devise two different story lines again. That would serve more of a purpose for game mechanics than for the plot itself, but it would still be fun and interesting, in my opinion.
I would also enjoy seeing Kairi's role in the story expanded. Your theory is proof that it could be if Nomura and team would be a bit more creative with her; I doubt we're going to see it happen with this game, but who knows? It's possible, depending on the ending of DDD, that she could play a pivotal role along the lines of what you're suggesting in another installment we receive prior to KH3. If they were to incorporate her into DDD in a R/R type scenario, I think it would be cool if she actually fought alongside Namine, somehow. That way, perhaps they could maintain some consistency with switching between characters even in the Realm of Light, since they're inhabiting the same Body; we could switch between Namine and Kairi, each have certain abilities which are practical or necessary for varying developments, and they would follow the same plotting unlike Sora and Riku, so they wouldn't have to devise two different story lines again. That would serve more of a purpose for game mechanics than for the plot itself, but it would still be fun and interesting, in my opinion.
