Mjolnir flies off (Thor has woken up from his drunken beatdown and I think it’s funny knowing he’s yelling in a desert somewhere, snapping his fingers and wondering where his stupid fucking hammer went. Also, this fixes any ‘hammer’ paradoxes for the first two games).
Ultimately, I think the game ends with Faye’s death. Another question left unanswered. She has one last epic battle, wins, but is too badly beaten for any sort of recovery. Battle to The Horn anyone? She’s bloodied, battered, jumps back in time to HER present to find Kratos.