Not real. Not worth talking about. The Elder God lines are directly from the previous games (Tony Jay has been dead for seven years, by the way), all the Kain footage is from Blood Omen 2, and Mobius' 'You have no idea what you've unleashed' is from his talking to Kain in Defiance.
Besides, the Soul Reaver storyline is tied up. Finished. Done. Forever. There is nothing to add to it. The series finished perfectly with Defiance.
If there were to be another LoK game in the same timeline that involved Raziel, it would be playing Raziel as one of the Lieutenants and the war against the Sarafan after being sired by Kain. As such, it would not be a Soul Reaver game, but it WOULD be a Legacy of Kain game.
As it stands, though? Hopefully there'll never be another one. The series is fine as it is. It's still just as good to play when it was released. Let's not fuck it up by adding chaff to an exemplary example of how of games can be vehicles for fantastic stories, like the Legacy of Kain, aye?This is where the Cathedral footage is from.