I think ultimately there is no good ending to be had due to our actual history, and the elders vision he saw of the future. I think war is inevitable and either Thorfinn will let himself die as a last attempt at peace, or he will just retreat to Greenland and give up. I think him sacrificing himself would be more likely of those two outcomes though.
As for this chapter and the future of the next handful of chapters, I think Hild will be proposing an assassination of those two and Thorfinn will disagree, of course. Maybe he ultimately changes his mind but still fails, but if they do get assassinated then that’s basically guaranteeing war by provoking the other side to the extreme.