Right now, there are two big things working against women making it into the NHL.
Development leagues that pay a living salary. Leagues like the AHL, KHL, SHL, etc. pay their players enough to live on. Players in these leagues can train full-time. The NWHL's (AFAIK, the best paying women's league anywhere) highest salary is around $25K. Women players need to be supported by others to train full-time, so many don't. If you want to make the NHL, training full-time is pretty much necessary, even if you are extraordinarily talented. Yes, some women players do train full-time, but this is a demographic thing. If most don't train full time, the odds of producing a NHL'er are low.
The Code. Look at the body types of players in the NHL. There are some tiny, slight of frame, quick and shifty forwards in the league that do extraordinarily well. Goalies are almost all well over 6'. Why is it that the closest women have come to playing in the NHL is as goalies? Because goalies almost never fight. The league prides itself on fighting. Any player can be called upon to drop the gloves if their opponent feels like they've made a dirty play. Players can drop the gloves even if it's just raw emotion. Any player on the ice, except the goalie, must be ready to answer the bell. The NHL also prides itself on being utterly wholesome, and that entails conforming to old-school gentlemanly conduct that includes never hitting women. "The Code" and traditional wholesomeness are mutually incompatible as soon as you put women into skating positions in the NHL. This, unfortunately trickles down to development leagues also.
Bottom line, until either fighting is eliminated from hockey or we all become comfortable with male hockey players punching female hockey players in the face, we're only likely to see women breaking into development leagues as goalies, and that's probably not the position women would be most competitive in.