Thorfinn will not die in Vinlnad, he will survive, and he will not be at 100% imo
If he were to die, it will be in Iceland. He has to live in order to see the failure and the consequences.
If a character were to die in Vinland, it will probably be- Ivar, Hild, Einar, or Ga'aoqi.
We are in the final arc, so i expect to see some deaths before the end, and it would be fitting and realistic as well.
Einar dying will be both tragic and poetic, since he will die in the village he fought so hard to build and to protect, and with Arnheid's statue being there, its just perfect.
Thorfinn dying ala Thors and Askeladd is also good, and then have Einar make a statue of Thorfinn- the IRL route.
Yukimura can really do something special for the end, and i hope he does.