His choices so far have taught us to expect the worst.
If Josh is playing a doctor and they follow the book, he shouldn't be the first one to get killed off.
BUT! They already cast 9 actors, Josh would be the 10th. I kind of think that the last one to join is most likely to be the first one to go.
I wonder where they'll place him on the IMDB cast (if the negotiations end successfully) list - maybe that could be indicative of how relevant the role is.