I would bet if Shelby is feeling good she will continue as long as she can, potentially doing the whole thing. The women's 10k time standard to qualify for Tokyo Worlds is a stiff 30:20, but I doubt many will achieve that so they will then go by world ranking. (they have not published the full qualifying system yet but they will only be taking 3 athletes from the World XC tour events)
If she is feeling good why not keep going and try??? Gives her another option because you never know...