To allow full contact in international women's competition, you would pretty much have to green light hitting in what are basically the women's equivalents of beer leagues. None of these players are professionals, none of them have ever played with hitting in their life, and no country besides Canada and possibly the US would have enough women to field both contact and non-contact amateur hockey leagues.
This would further widen the gap in Canada's favor, as we already have a significant size advantage over all other teams (no doubt due to the massive player pool). The sport definitely needs to grow much much more on the worldwide stage before this can happen, and hitting would have to be adopted in minor hockey first. This is completely different from the origins of men's hockey, where everybody used to have to play with hitting - house leaguers, minor hockey, you name it. It was only relatively recently removed for low level/D league players and with the emergence of the beer league.