A Deadly Ending Can Still Be A Happy Ending
Few would argue that the Winchester brothers aren't deserving of a good, long rest. If Supernatural does indeed bid farewell with the Winchesters' deaths, the final scene can still be a positive and uplifting end to Sam and Dean's story. Given the family's history in heroic deeds and their personal friendship with God himself, it's possible that when Sam and Dean die, they won't depart to the afterlife like just any regular old humans. Instead, God could use his position as the general creator of all things to offer Sam, Dean, Mary and John a place in the heavens where they can live together in peace for all eternity. Combine this with a hunter's funeral led by Castiel that draws in powerful hunters from across the globe, and Supernatural looks perfectly positioned for a touching, but permanent, sendoff.
Even with such a heartfelt resolution for the Winchester family however, there would still be a lingering question mark over the safety of Earth. Who will protect the world, or the U.S. midwest at least, without Sam and Dean around? Supernatural may have already laid the groundwork to provide a solution to this very problem.
In the recent Supernatural season 14 episode "Don't Go In The Woods," Sam and Dean were forced to give "the talk" to an ignorant member of the public. Instead of staring at the Winchester brothers in disbelief and awe however, this person questioned why the duo hadn't already revealed the truth about the supernatural to the entire world. While Dean scoffed at this idea, Sam appeared to be seriously considering the proposition, and thus the seeds were planted for brotherly division further down the line.
With the end of Supernatural now in sight, this scene may well be laying the foundations for an ending that sees the Winchesters reveal the truth to the entire world before departing the mortal plane, leaving Earth's fate in its own hands and answering the question of who will guard the planet without Sam and Dean around.
At its core, Supernatural has always been a show about sacrifice. Sam and Dean Winchester have sacrificed any opportunity to live a normal life in order to protect the world from evil and, somewhere along the way, they seemed to silently accept the reality that there was no running away from their destiny as hunters. Changing course in season 15 to give the Winchesters a fairy tale ending where they live to see another day would not only feel wrong, but wouldn't fully close the book on Sam and Dean's epic journey.
Supernatural season 14 continues with "Game Night" April 4th on The CW.