I don't see a problem if she is qualified. Most coaches have a team of assistants so they do very little coaching themselves.It is more like overseeing the job making sure the team is doing the correct things properly.
It would be a breath of fresh air and just maybe the men would perform better and stop with their play acting on the pitch.A footballer is an athlete and it doesn't matter what sex coaches them.
The world is changing and it is a possibility in the future.Football is not what it used to be and is no longer a contact sport as such.I agree it is male dominated at the moment.but it just takes one. We have women owners of clubs so why not a women coach.