Something tells me the status quo with Hel has to be addressed to eliminate her as a threat. I don't see her getting Snarled/fading away before the story ends. There's two ways I can think of to resolve her arc.
1) Durkon, knowing about how she doesn't need a full blown church to survive, just worship, gets the Dwarves to pray for the Dishonoured, asking Hel to be lenient with those who died in shame. While not an ideal situation, it could work to stop Hel being so invested in this world's destruction.

2) Loki, as bet broker, and Thor, as the competition, both agree to end the Bet prematurely. If all parties are in agreement I don't see why this wouldn't be possible (unless, as I've considered before, deific bets are hard-coded into the universe and can only be undone by unmaking reality). However, to end the bet, Hel will have to back down, either admitting living clerics are more important than souls in the long-term, or accepting the end of the bet when her masterplan could still turn around (see Sunk Cost Fallacy).

Thoughts?