But here's my only problem with this specific scenario of Psycho Mantis:
If we go by what we know, from Peace Walker and from Ground Zeroes, Big Boss is against CIPHER, and XOF (headed by Skull-Face) are against them as well. This is why I assume that the two of them are working together. So, my assumption is that we'll see the Big Boss/Skull-Face answer to the FOX unit, XOF, turn into FOXHOUND (literally, a hound that hunts foxes).
So, I'm wondering how that would work, if Skull-Face (and I assume Psycho Mantis is affiliated with him, judging by the trailer he appears in) would use his psychic powers to control Diamond Dog soldiers to attack Big Boss and company, and then WORK with BB?
I think we're missing something here. Especially considering that Psycho Mantis didn't officially join FOXHOUND until after Solid Snake completed his mission in Metal Gear 2. Frankly, I can't wait to see what happens, but I'm thinking Miller is the key here... I'm positive that, even in his quest for revenge, he realizes his mistake. But Big Boss doesn't, and that's where the rift comes from, if there is one, between him and Miller.