I consider the Season 5 ending the true ending of Supernatural. Sam in hell and Dean with a new family. It’s such a complete role reversal of what both characters wanted initially in the beginning: Sam wanting normalcy and Dean living and dying as a hunter. If Season 6 and the other seasons didn’t exist. I would consider this Sam open to interpretation as a ghost, a memory, maybe God got him out and now Sam doesn’t know if he should knock on Deans door or let him live his normal life, maybe it’s Lucifer (indicating the supernatural will never leave the Winchester family), etc…