User blog comment:Blaziken rjcf/My prediction for Alpha and Omega/@comment-26992577-20160527045218/@comment-109.66.36.57-20160528134818

Removing Azazel from existence would basically delete all of the events in Supernatural.

If Azazel never existed, Mary would not die and Sam won't be fed demon blood. John literally became a hunter because of that. He wanted revenge on Azazel for killing his wife. John would then never become a hunter, and so Dean and Sam as well. In season 2, Dean sells his soul to a demon to save Sam, which later causes a rightous man to go to hell - the first seal. If Dean and Sam were never hunters, John would still be alive, and the seals won't be broken - Lucifer would still be in the cage. This also cancels the rest of the plots, as Castiel won't need to absorb Purgatory to fight Raphael - he will still be a soldier unaffected by Dean and Sam. Raphael, Michael and Gabriel will all be still alive. The Lavaiathans won't be freed. The Tablets won't be discovered. Kevin won't become a prophet. Metatron won't use the Angel tablet to cast all angels out. Dean won't try and kill Abbadon, and won't have the Mark of Cain, meaning he and Sam won't try and remove it and free the Darkness. If the Darkness is never freed, she could not send Dean back in time like you say, and God would still be hiding.

TL;DR: this idea literally cancels every single thing that happened in Supernatural. As of the British lady, I believe she either shot Sam in a non fatal place, or missed him as a warning.