Given how drastically Microsoft changed in the last couple years, I wouldn't be surprised if they distanced themselves from the level of compatibility guarantees they issued in the past.

EDIT: I don't think it would go down well, if some files cannot be opened in all applications only because of the path. I mean, Windows is the biggest enviroment for the most diverse set of desktop applications right now, so refusing to open files because your app doesn't support the path sounds unreasonable but I cannot think of a solution myself. Thus I'd like to know how they're approaching this.