I believe Kingdom Hearts 3 will end with the death of all 7 Guardians of Light...
...Okay well maybe not "dead" dead, but here me out...
There has been a lot of chatter that the 5 "Lost Masters" are actually:
[it is believed these are the lost masters due to color scheme comparison, height equivalents, and the use of the same voice actors, I would recommend looking into this more yourself if your skeptical (Rebirth Theory w/ Pics = http://forums.khinsider.com/kingdom-hearts-iii/194630-rebirth.html and GamersJoint voice comparison https://www.youtube.com/watch?v=8rGI_Yzr2cI ]
Aqua = Anguis
Ventus = Leopardos
Riku = Unicornis
Terra = Ursus
Kairi = Vulpeus
...with the sixth lost master being missing
It is also believed that the missing final page in the Book of Prophecies is also the page that states that darkness will triumph over light...
Now here's where my theory begins, what if the Book of Prophecies was written by "people" from the future in order to try to prevent the outcome these "people" had faced (darkness defeating light)? So as to say, the Book of Prophecies is actually less of a prophecy written by the foretellers, but more of a recollection of past events the foretellers/"lost masters" actually experienced? This would mean that the "people" who wrote the Book of Prophecies only knew what happened up to the point of darkness defeating light, NOT what happened afterwards. I emphasize this because it seems as though the Book of Prophecies is incomplete and limited (the prophecy ends at a point that I can't possibly see as being the ending) and I think that's because its not the ending, but rather, just as far as the "lost masters" were able to make it before getting sent back in time! (Maybe through the power of finally achieving Kingdom Hearts) Now I want to quickly focus on the term "LOST masters". What makes the masters "LOST" and if the Lost Masters are the Foretellers, why are the Foretellers LOST??? I believe its because after the great war/clash between the 13 SoD and 7 GoL, 6 keyblade masters in the fight disappeared, not to a new location, but to a different time. So what if, at the end of Kingdom Hearts 3, Xehanort had finally captured Kingdom Hearts and the world fell to darkness, but as this happened, somehow Aqua, Ventus, Terra, Riku, and Kairi were sent back in time (along with the other unknown master) and became the foretellers.
[Here's where the theory becomes a bit difficult to explain since we dont know who the GoL or the missing foreteller is, soooo from this point it's more random speculation than a theory backed by context clues]
The crazy thing here is that Mickey, Axel/Lea, Sora, and Xehanort (not accounting for Vanitas, as I believe he may be defeated prior to this point) are all unaccounted for. I speculate that it could be possible that Mickey, Axel/Lea, and Sora are presumed dead by Xehanort, who finally achieves Kingdom Hearts. I speculate Sora and Axel/Lea "die" first. Then Mickey, in a last ditch effort, somehow manages to send Aqua, Ventus, Riku, Terra, and Kairi to the past to prevent the future, and "dies" doing so. Thinking they are all dead, and knowing the 5 were sent into the past, Xehanort goes into the past as the 6th/final foreteller(lost master) to steal the page from the foretellers as an attempt to prevent the world from knowing the truth that the events in the Book of Prophecies would lead to Xehanort's victory (so as to prevent anyone that were to read the full Book of Prophecies from ruining his plans). This would allow him to orchestrate a long drawn out plan manipulating even his younger self into following in his footsteps by mentoring Young Eraquas and Young Xehanort as his pupils. He would then use his ability to time travel to points in which he existed to return to the battlefield at the end of the game to finally sit on his throne ruling over the darkness in the world. However, I believe Axel/Lea will have died shielding Sora again (but this time he dies for real), and Mickey isn't dead but seriously injured and can't move. This would leave Sora and Xehanort to battle it out for one final showdown after the annihilation of the entire crew, the Book of Prophecies to have been fulfilled and for the Xehanort saga to be entirely tied up of loose ends. This would also account for Sora continuing on in his journey in the next installations of the game as the main character (as Nomura had stated would be the case) and would leave Kingdom Hearts X as more of a "side story" with the final page within the book of prophecies to actually be fully canon (which is what Nomura had stated would be the case of Kingdom Hearts X in relation to KH3). I also recall Hashimoto or Nomura, earlier in KH3's development, saying that they planned to make the ending sad, but Disney told them it was too sad and that they wanted a happier ending. And I believe this ending is sad enough for Disney to speculate it.
OKAY SO WHAT DO YOU GUYS THINK?
Do you guys think this is plausible?
Do you think this makes a lot of sense but maybe a little different? (such as Axel/Lea actually being the 6th Lost Master, but is Killed by Xehanort and framed as a rebellious lost master?) (Or even the 6 Lost Masters are the 7 Guardians of Light minus Sora?)
Am I missing anything such as the use of the X-blade in KH3?
Is there anything you'd add or subtract from this theory?
Please let me know!! ^_^