From Movieweb interview
According to a highly reliable inside source, fans hoping the third Winchester is some kind of trixter manifestation or easily undoable Kripke mind-frak - sorry! The word is that the new Winchester, Adam, is the real deal. How solid is this intel? 99.9% Probable. That leaves a meager margin for the incredulous to cling to. Now here’s the thing. The source says that while everybody may be focused on whether or not Adam is legitimately John’s illegitimate son, come Friday morning we’ll be talking about an entirely different wrinkle in the Supernatural drama. Look for a twist ending that strikes from north of nowhere.
BOOO to the Jump the Shark spoiler. :-P