"What If Jane Foster Had Found -- the Hammer of Thor?"
Synopsis for "What If Jane Foster Had Found -- the Hammer of Thor?"
Jane Foster found the hammer of Thor. After some instances of her helping in Asgard against Loki and an alien invasion, she was promoted to a goddess and the hammer was given to Donald Blake, as it was supposed to. Thor got involved with Sif and Jane Foster married Odin.
This What If...? story came to fruition almost four decades later in 2016 when Jane DID get the hammer and became the Mighty Thor in continuity in the Marvel Universe.