My impression is that they will find a vial, or something to that effect, that let's them cure Tuuri but little more.
As such they can then come back to Iceland with something much more valuable than books - the possibility that out there, in the waning days of the last campaign, someone found a remedy to the plague, but in the disastrous retreat it was abandoned/destroyed/compromised.
So now they can have a second round of adventure, with better funding, to gather information and perhaps find the promising serum.
At least, this is what I interpret the ghost nurse tidbits to be a lead for.
The only problem with this theory is that I still firmly believe that the disease is of a metaphysical nature as well. So at best they will be able to find something that slows the physical symptoms, but not a complete and total cure. Save her body, but her soul might still get infected. Possibly she will then fall into a coma until Lalli and/or Reynir goes into her mind and save her magically as well.
