Roxor: I think Ignatius's status as Tzeentch's vessel owes to some god-fallout embedded in him after Ahriman killed Tzeentch on Cadia. (His story about being exorcised by proximity to Ezekiel seems plausible. Curiously, there's a retconned-out bit of 40K
background material about how being possessed by a greater daemon and exorcising it makes you immune to Chaos.) But I think it makes sense to view whatever just talked to him as more than your standard Lord of Change.
That said, Tzeentch in his full glory couldn't foresee Ahriman shivving him with a reforged phase blade, so there's no way this latter day knock-off should be able to make accurate predictions concerning the C'tan, their Necron hordes, or the pariah knights.
Slaughter:
Also, its just me or Tzeentch implied Khorne or some fraction of him is alive, or may be reborn?
The Dark Gods were born out of particularly strong emotional excesses; Root's continuity changed their back story a little, but I think that's basically intact. It's also been pointed out that declaring that war is god isn't much different from worshipping Khorne; Judge Holden and Kharn would probably get along pretty well. Or do whatever their equivalent of getting along was. Murder each other, I guess, but like respectfully. Anyway, a whole universe of humans living by the creed "WAR FOR THE WAR GOD" is probably going to see the reemergence of a Khorne-like deity.
B.) " In another future, I see the Winged Serpent without wings and the screams of the dying as their blood mixes with the metal of the undying, both bound to the same fate, for there can be no peace this side of the grave."
Winged Serpent is most likely the Dragon, as in the Swarmlord's vision; him being without wings suggests he's been denied ascension. The undying are the Necrons and/or the Grey Knights. The outcome here is uncertain; being "bound to the same fate" could really mean anything. Death, slavery, deliverance.
According to you, this is B. You're only half right here. The winged serpent without wings is The Dragon, denied his ascenssion, but the Metal of the Undying is the Necrodermis. I think the dying are the dead, the blood is actually the Warp, and the mixing is actually the Nightbringer dying as the warp rift expands into Mars. I have to admit, this played better than my Mars' Penisgun shooting plan. No peace this side of the grave sounds like the TOTAL WAR EVER AFTER FOREVER future Tzeentch showed us
Eh, I voted for this one partially because it seemed like the most ambiguous prediction, and the meaning still looks unclear. The Void Dragon is the strongest candidate for the winged serpent, and we've even seen the serpent + aquila motif before, but it could be the Swarmlord (most of the Imperium thinks he's the dragon of Revelation, and his hive fleet
is named "Iblis") or even Tzeentch (his daemons had that retarded avian theme, and calling him a serpent doesn't seem like a stretch). Neither of these alternatives make sense if you assume the Winged Serpent from the Swarmlord's vision is the same as the one in Ahriman's, though.
The mixture of blood and metal of the undying sounds a lot like the Grey Knights, who will probably battle the Tyranids under one emperor or another. Your take is just as likely, though.
Ghosts: Necrontyr
Ancient Ruins: Necrontyr homeworld.
Promises of Liberation: Failed Necrontyr attempt at being free from the C'tan.
Old man and lithe white figure: Marius Hax and The Deceiver.
Blazing Sun: Interesting, another sun. It scorches here too. I think this is the original Emperor, but it might be AI version too. There's the possibility it is The Great God, too.
Winged Serpent: Void Dragon
Carved Gemstone: Machine God/AI Emperor. It "outshines" the original because it has more psionic power, for there is no more God in the warp
Hall of Mirrors: Infinity Circuits of the Craftworlds?
Trapped Souls: Souls of the Eldar?
Place where knowlodge went to die: Black Sands? The Warp?
The blazing sun definitely sounds like the Emperor as the Machine God, as consistent with Ahriman's third vision. The sun smiling at the serpent suggests the Emperor Machine's cooperation with the Dragon's goals, as the Malcador Mind outlined. Regarding the ghosts trying to drown the serpent: this was never spelled out, and maybe it's been obvious to everyone else, but my guess is that the Necron fleet that just showed up is under the control of the Nightbringer, not the Dragon, and it wasn't trying to protect Mars; that was an invasion.
The place where knowledge went to die is the Black Library (Iblis took a detour there between Calixis and Terra). I think the Hall of Mirrors and Trapped Souls can't be the Eldar, though; I think the Infinity Circuits of every craftworld merged with Khaine to power him up for his duel with Slaanesh, so presumably they're free in the warp. I'd guess the trapped souls are Necrontyr--maybe the Swarmlord wants to liberate them from the Necrons?