Ill consider some new ideas and argue certain storylines based on factual presented data in texts or pictures. Read carefully and judge for yourself
What happened at the world stone:
First of all you need to know what actually happend when the world stone was destroyed on a factual basis from the books:
1# Sanctuary is visible to demons and angels making it a possible (and probable) battlefield for heaven and hell
2# Humans will (probably slowly since its been already a few years since the world stone was destroyed) regain their hybrid angel/demonic powers
Conclusion: Way more powerfull creatures are set loose on sanctuary resulting in a complete chaos :P
PS you can find all this info from the book
"In the Diablo: Sin War trilogy written by Richard A. Knaak, it is revealed that Inarius along with other rogue angels and demons are responsible for the creation of Sanctuary and the Nephalem (Angel and demon hybrids with great power). Inarius wished a Sanctuary away from the constant battles between demons and angels as well as create his own High Heavens which would be greater than the original. However the development of the Nephalem's powers infuriated Inarius making him want to start anew by eradicating all the Nephalem. This brought him into conflict with Mephisto's daughter, his romantic partner Lilith. Due to the conflict between the two Inarius banished Lilith. This is because Lilith desired to be a tyrant with an unbeatable army under her control while Inarius wanted lowly worshipers. But before Lilith's banishment, Lilith had killed all other angels and demons on Sanctuary preventing Inarius from destroying the only sentient being left on Sanctuary, the Nephalem because Inarius did not wish isolation. And so Inarius used the worldstone to prevent the Nephalem from developing their powers, reducing each succeeding generation's powers until they became the mere normal humans of Sanctuary. Inarius also used the world stone to mask the existence of Sanctuary from his own Angelic kind in the High Heavens. He then later created the religion Cathedral of Light to make the beings of Sanctuary worship and serve him."
So now we start theorizing with reason as to what happened to Tyrael there:
What happened to Tyrael:
The world stone was corrupted so Tyrael had to choose the lesser of 2 evils, either the world would become corrupted or it would remain the way it was but become visible to both hell and heaven. Obviously the second choice was the best (else there wouldn’t even be a D3 :P ) The big question remains is Tyrael corrupted by his deed of "evil" it’s hard to say because the world stone was already corrupted so technically he destroyed evil but then again what would the blast do and was he even allowed by heaven to intervere?
If you look at the D3 picture however you see a interesting thing, the bottom of the head is Diablo.. but the upper part seems holy? It might be that tyrael was corrupted as he seems (also from the opening page of d3 website) to be a main npc in D3. this last part is just a guess not a real good theory, lets continue:
The interesting fact of humans becoming demon/angels hybrids might even suggest a choice.. like dark or good.. this would then mean additional skills in that regard.. and.. yes PVP
Also as Vivendi announced that all blizzard franchises will eventually become MMO's its also a setting of the sides: Demons vs Angels (like horde and alliance) This thought isnt to attrative to me at this point but its quite conceivable
It is very likely tyrael was corrupted in some way.. maybe not completly but atleast a bit, you see millions of shards comming from the destroyed world stone.. its quite likely he got hit by some corrupted shard pieces...
Why tyrael probably got corrupted:
#1 What would be a better boss then Diablo possesing Tyraels body? Would also explain the weird look of Diablo in the cinematic trailer
#2 Tyrael destroyed the world stone which was corrupted at that time, thousands of shards flying everydirection.. would be hard not to get hit..
#3 in the Diablo 3 cinematic you actually see Tyrael throwing his sword in the world stone.. why would they show that? If they already showed it in D2? because in D3 you see how it ends now.. Tyrael gets struck by a shard
4# Noticed the weird D3 logo? its not entirely evil! The top seems holy... the bottom hellish which also hints towards a corrupted tyrael fighting the darkness within. This also makes sence if you think about the Demon/Angel human nature awakening.. some have argued that its just heaven and hell, but it seems like its the crown of diablo almost like he is dibalo but still with a part of tyrael in him
5# Everyone agrees you can’t have a Diablo game without a Diablo.. how can that be? His soulstone was destroyed... well who ever said their soulstones cant just be reforged... specially by.... an angel? who better to be able to forge a new soulstone then Tyrael! A angel! corrupted by a corrupted world stone.. that power should do I guess :P
6# Tyrael fighting the corruption within would explain why none have heard from Tyrael in 20 years! He fought the darkness inside! That tough guy! He sure as hell didnt die in the blast (since you see screenies of him check the link below)
7# What is the meteor? Tyrael! He has been battling the corruption from the corrupted world stone for 20 years in Heaven.. but finally succumbed.. therefor he is casted down by his bretheren: Voila corrupted Tyrael falling from the sky
Check the pictures from the great tyrael corrupted or not post.. confirms this story:
http://www.diablofans.com/forums/showthread.php?t=9443
8# Okay look really closly in the picture where you see the Tyrael movie sequence.. do you see hes in a cathedral? also hes in a cathedral on the main D3 page like Gnub said.. now this doesnt prove that its Tyrael who is the meteor.. but its more and more likely that he is since the meteor clearly crashes in the cathedral as seen on pictures. Also you see a black and white drawing of tyrael, with a figure in front of him.. Deckard Cain! Who was in the cathedral as the meteor struck.. Another hint is given by the fact that his wings are.. redish... like evil! in any other pictures/movies of tyrael previously his wings were PURE white
Now it says this on the front page of D3 website:
"The comet carries a dark omen in its fiery being and it calls the heroes of Sanctuary to defend the mortal world against the rising powers of the Burning Hells – and even the failing luminaries of the High Heavens itself."
So IF Tyrael is the meteor which seems likely given these factcs then its also likely that he is corrupted in some way as the text says "The comet carries a dark omen in iets fiery being"
Now this sentence is pretty important: "and even the failing luminaries of the High Heavens itself." So read carefully: The comet is a omen TO : The failing luminaries of the high heavens itself.. how can it be an omen for that if its not a corrupted fallen angel? or somethign of the sort!
(A demon landing woudnt have to be a omen for that for example, but a fallen angel would)
9# noticed the picture where Tyrael (or another angel) is laying in the air with angelic signs on the floor.. Perhaps Tyrael being kept improsoned in heaven? seems like hes in some sort of strugle.. with angelic icons on the floor.. and again with the first glimps of redish glow on his wings
"10# Once we vanquish Diablo Tyrael is freed from the corruption.. awwww such a happy ending!:P "
I’ve compiled my theories from different topics im curious how you feel about all this information together
Cheerz
Ill try to keep this post updated so check it if your intrested!