In addition, the Foretellers do have one thing in common with Master Xehanort: their respective Keyblades have this blue eye embedded on the key chain. MX's Keyblade has one as well, though on the shaft instead of the key chain.
Also, I'm not sure if I'm seeing things that aren't there (I think I am), but the Unicornis Foreteller seems to resemble MX somewhat. That metallic piece he (assuming the Foreteller is a he) wears on his head forms a goatee-like extension on the chin. Of course, anyone could wear that piece and
look like MX especially with most of their face obscured, but still... I can already envision a face resembling MX's hidden underneath that unicorn mask.
The blue eyes, though, have to say something. There's no way they are there for no reason. I wouldn't be surprised if later on MX turns out to be connected to the Foretellers somehow. It could be that he was the sixth disciple, it could be that he was the Unicornis Foreteller, we don't know, but I'm putting dibs on the possibility of a relation existing between MX and the Foretellers.
To be honest that looks more like the metallic jaw-piece Vanitas wears than anything MX-like.
So far we know only that this "blue demonic" eye has something to do with Darkness, as all shown items sporting that emblem had something to do with Darkness and were mostly used to cause destruction.
Considering the time of the Foretellers and the whole Keyblade War is said to have happened tens of thousands of years ago Xehanort logically couldn't be anyone of them nor the sixth follower as according to history all of them experienced the Keyblade War first-hand.
Xehanort in his curiosity and madness yearns to know what exactly happened during the Keyblade War and thus seeks to restart it even if that means the end of everything. He wouldn't need to do that and seek these "answers" if he was already present at that time since he would have experienced it first-hand either as a foreteller or as the sixth disciple...
I won't deny that there is possibly a connection/relation between Xehanort and the foretellers, but I doubt it'll be something that results in Xehanort being actually alive during the times of the Keyblade War.
No, in fact I'm thinking about a more sinister variant and a twist that would be worthy of Nomura. I don't play Chi and thus do not exactly know how the foretellers act and what they do, but the fact that they have this eye on their Keyblades, the tomes they got apparently "predicting" the future and the phrase "light falls to darkness", I'm actually suspecting that the Foretellers are the ones who eventually bring about the Keyblade War themselves, possibly because each one deciding that he/she possesses the right path/strategy to avert the apocalypse and thus should be the only one leading the "forces of light". Under the Foreteller's leadership, the unions turn against each other and one wielder after the other falls to darkness.
This way, the Foretellers bring about the very apocalypse they wanted and fought to prevent by their own actions, possibly even driven mad by the books of prophecy they possessed because the events predicted there were what got them to take up arms in the first place.
The sixth follower, the only one without a book, would be the only one to remain sane and possibly even the one who helped and guided the surviving children to eventually rebuild the world.
Going from that assumption, there is this snippet from the Xehanort reports in BBS:
Xehanort's Report II said:
Our Master instructed us to don armor while traveling between worlds, so that we might shield ourselves from the darkness. But there, in the Lanes Between, I could feel the force of it—the power—and from then on, I forwent my armor's "protection." I had been told the darkness would devour me, but what terrors could it possibly hold, so long as I found the strength to control it?
Then there is this from the new teaser:
E3 Teaser said:
Then I take it you also know of the "lost masters"
On that land shall darkness prevail and light expire. But you knew that, didn't you?
We already have a place where "darkness prevails", that being the RoD itself and, curiously, the lanes between themselves.
When Xehanort stopped to use his armor and went travelling without protection from the Darkness, who is to say that he didn't
meet something or someone out there? Something or someone "lost" out in that sea of darkness since ancient times.
It is said that Xehanort gained much of his current knowledge from very vast and long travels, yet who says that those travels had to be all within some specific worlds?
In DDD, Ansem SoD tells Riku that "Darkness holds our sleep" and Ansem the Wise later speaks of "Hearts sleeping in darkness" like Roxas, Ven and Xion do within Sora's heart. However, worlds have hearts as well and I assume that the original, undivided world also had a heart.
What if all the people of the old world, including the foretellers, who perished in the grand apocalypse that destroyed everything, are actually "still around" in the form of their hearts sleeping somewhere just like Roxas, Ven and Xion do within Sora?
This somewhere would be of course for most existences the true, original Kingdom Hearts itself, but what if some hearts were for whatever reason not returned to KH but sleep somewhere hidden in the darkness of the lanes between or the RoD? These would be as "lost" as the tormented ones Sora is supposed to save who are connected to his own heart (TAV, Roxas, Naminé, Xion and AtW).
I wouldn't put it past Nomura that Xehanort, having essentially the same ability to connect hearts as Sora, somehow made "contact" with the hearts of one or more of the foretellers, gaining some information from connecting with them. Since I doubt the foreteller's were all-knowing, the snippets of info Xehanort would get from them would only serve to increase his curiosity even more, leading to his increasing obsession to maybe find the hearts of the other foretellers, maybe even the sixth disciple and one of the books of prophecy in order to gain knowledge not only on what exactly happened in the Keyblade War, but also on the true nature of the X-blade and the true KH.