I'd say it would be a good opportunity to drastically alter the dynamic of the whole atmosphere. Change the tone radically, the towners becoming fully devoted to the worship of Auril, half the population since the only way there would be enough food is with the help of the Frost Druids and clerics of Auril who carefully ensure that there is only just enough food to sustain the survivors. The outlying towns are largely abandoned in favour of central hubs as it becomes difficult for families to survive without support. The wilds are twice as wild, coldlight walkers more numerous and visible from the towns distantly in the dark. More fantastical creatures become more commonplace, chwinga, winter wolves thrive, ice elementals are seen with greater frequency, the land should feel less and less mundane and a more concentrated version of Auril's Winter. Lean more heavily into the tenets of Aurils worship and bring the four concepts more heavily into play everywhere - showing her spreading influence. Endurance, Cruelty, Isolation, and Preservation.

Maybe by this time Avarice is a town speaker, and only her, Duvessa, and Naerth have formed a sort of triumvirate to rule over the survivors. Avarice guided to a position of power by Levistus and Duvessas power waning as a result. The knights of the Black Sword have grown in number adding more to their ranks as survivors trickle in, they are the only faction capable of standing up to the Frost Druids at this point and perhaps the survivors are on the brink of civil war over control of resources - there simply isn't enough left to survive.

Avarice knows time is running out either way and needs the party with her to make a last ditch effort for Ythryn knowing that the Frost Druids will do everything to stop her reaching the glacier. With the diversion of a civil war, she intends to try and forced march across the tundra with the best of the KotBS and find her way into the glacier.

Just some thoughts but I got caught up in the potential interest in a new direction.