It's not written vaguely. When you complete the ritual you live and when you don't you die.
but to cut this tangent short http://forum.bioware.../#entry15371761
The ritual is ill defined. Morrigan tells The Warden s/he will live if they do it and her word is all we have, and it could be she adds surviving as a perk for The Warden getting it done. We don't know how it works. We only know what Morrigan said.
I also already knew about Gaider's comments and I appreciate the BTS clarification from him. Interaction like that is one reason I adore Bioware. That however still doesn't mean anything in-story until the games display it such.
eg. Han shot first, George says that was not intended, George alters it to display the certainty. Sherlock is not Khan, turns out he was Khan.
By the way, I don't recall who said it but it was a Bioware mouth which said we could discover that what people in game have told us may need to be re-examined as to whether it's true or anything in between. As in having agendas, control of information etc. "From a certain point of view." Type thing.
All I'm saying is that this really comes down to being open to possibilities or insisting something can only be something. This is true for those pro-OGB and those which aren't.