Hard to see anybody kicking Nordstrom off the roster. He's a good match for Kruger and he can play either wing. I think we're probably pretty happy going into the season with a 4th line of McGinn/Kruger/Nordstrom.
Ryan is the one whose spot seems most vulnerable to me. If a winger like say Zykov/Gauthier/Foegele/whatever comes in and blows the doors off, then he goes into the top 9 and Teravainen moves into the 3C spot. Or if Wallmark or Roy comes in and looks good at center, then either one could relegate him to the 13th forward. I don't see him fitting into a 4th line role. This is not a bad thing - if you have a Derek Ryan as your 13th forward instead of say PDG, you're in pretty good shape up front.
I don't think he is a lock for that spot at all. PDG could easily challenge him and I wouldn't count out McLovin' from making a run at that spot, either.