Just got caught up. Certainly hoping for the best - we now know that something is happening, which is more than we have known in nine years.
I'm hoping desperately that a distant continuation - ala Star Trek TNG or Doctor Who 2006 - is chosen over a reboot. Heck, I'd even take an alternate timeline/prime timeline thing ala Star Trek XI.
The event "War for Nosgoth" can describe multiple conflicts in the canon:
Vampire/Hylden War - in the prehistory of the games. the spiritual Vampires (guided by their parasitic God) fought the scientific Hylden for the whole of creation. The war devastated the world until both races unleashed their WMDs: The Vampires activated The Pillars and they threw the Hylden out of the universe into a reality of pure pain - and the Hylden activated a biological weapon infecting their enemies with a combination of immortality (an imprisonment in flesh, as the Vampires worshipped death), sterility (no more Vampires) and blood thirst (to ensure that the rest of Nosgoth would hate and hunt them). The war is only told in ruined mural, "written by the victors" - and a known fortress from the war has a buried dragon skeleton (Avernus Cathedral depths in Blood Omen) suggesting that dragons were employed by one or both sides.
Sarafan/Human-Vampire Hybrid War - seen extremely briefly in the intro to Blood Omen, this war was fought between the human Sarafan (first army) and the human-vampire hybrids. The humans - led by the wizards of the Circle of Nine - engaged in a campaign of genocide against the human-vampire hybrids. The result - referred to by the survivor Vorador - was the near-extinction of Vampirekind.
Nosgoth/Demons During Blood Omen, a race of Demons invaded Nosgoth through a foothold in the gargantuan Avernus Cathedral. They flooded out of the church in huge numbers, and murdered everyone they could find in the unprepared religious city. The invasion was stopped when Kain entered Avernus, found the Planar Azimuth - the focal point of the Demons - and murdered her. This war was stopped before it fully began.
Nosgoth/Legions of the Nemesis - Nosgoth's Hitler - William "The Just" - raised an army of the most monstrous humans in the North. They launched an onslaught of rape, disembowelment, torture, and pillage throughout the free towns and cities. The war came to ahead with The Battle of the Last Stand - in which King Otmarr led the last Army of Hope (and Kain) against the invaders. The invaders prevailed, the Army of Hope was massacred, and Kain escaped using a time machine - travelling back in time to murder William in his youth so he could never become a tyrant. The war was erased from history - but as Soul Reaver 2 shows us - some people have a destined time of death. Presumably, some other war broke out to kill all the people that were meant to die in the war that was erased from time.
Kain/Sarafan (Second Army) - Kain led an army of human-vampires across the world, murdering all that challenged them. The Sarafan Lord (in reality the Hylden General - his spirit projected into a clone body from his prison within the Demon Dimension) trained a new army of Sarafan enhanced with Hylden technology and science. The Sarafan were not expected to be as advanced in training and ability, and destroyed the majority of Kain's vampire hoarde. Kain's first invasion of Nosgoth was defeated.
Kain's Empire/The World - Following the events of Blood Omen 2 Kain raised his Vampire Lieutenants (Raziel, Turel, Dumah. Rahab, Zephon, and Melchiah) who were each able to sire clans. This army - all of Kain's blood - declared war across the land. Humans were enslaved and domesticated. Dark towers were built to block out the sun. The vampires - though outnumbered by the humans - were able to win the war and conquer the entire world for a thousand years. This War for Nosgoth transformed the planet into a death world.
The humans/The Razielim/Kain's Remnant Empire - The final war took place after Raziel's execution. The Razielim were wiped out by an uncertain party. Kain vanished from his role as Emperor, and the world fell into disarray. The humans launched a war on the Vampires - one wave was successful in invading the Dumahim City, scattering the clan and impaling the great vampire Dumah on his own throne. The humans assembled a weapon of sound - known as the Silenced Cathedral - which upon completion would have been a WMD able to create a resonance frequency that would destroy all vampiric life across the entire planet. The Zephonim clan invaded successfully and claimed the weapon as their own - murdering the humans that worked on it. The vampire leader Turel vanished entirely (in reality he was summoned into Nosgoth's past to play as a host body for Hylden souls). This final war led to Nosgoth going from death-world to wasteland. The vampires were scattered and their temples ruined. The vampire leaders devolved into beasts and hid away. The humans were generations away from complete extinction. The world shook with instability and the end of everything was near.
So, in short, if the title War For Nosgoth refers to an event mentioned previously in the canon of the series, it could be any of the above.