What if at the very last episode of supernatural, everything pans out and we see an angel sitting by Mary, and it turns out everything we've seen was everything said angel had showed Mary in order to prevent her from having a second child by saying that all this tragedy and heartbreak would be on him were he to be born. So we see Dean growing up as an only child, succeeding in his studies and career, and eventually raising a cute bright eyed and dimpled smiled kid called Sammy