women playing against women may look like they are good, but, i had the chance to scrimage against 1/2 of a team canada womens gold medal winning team, (dont think Wickenheiser was there, as she'd have been too young still ...i'm a 'bit' older than her) and let me just say, that 2 of them were pretty good, as they were great skaters but the rest sucked. ...and the 2 'good' ones were good enough to play on a mens beer league team at best,
so, there's the realty of it.
other than as a goalie, its highly unlikely to ever happen, unless she is an exceptional physical specimen that you will ever see a woman in the NHL other than as a publicity stunt. ...i mean if a guy can play at 160lb and 5'8" then an equally talented woman should be able to as well, but, lets have one dominate the OHL before we think of the NHL.
baseball should be possible though, surprised none have yet.