So is it possible that if the eruption had been left alone, something similar to Corypheus' dragon could have been born? One that has similar power over the Blight like an Archdemon did?

I wrote off the whispering at first as just something creepy, but then remembered that Corypheus was able to cause a fake Calling in DAI but it was never really explained in detail how he achieved that. Nor how he got what everyone thought was an achedmon on his side

This might just be a shot in the dark, but with the way the Blight is being described as growing and changing, makes me also think of how the achievement for unlocking the secret ending is described as the posioned fruit has ripened.