I am all for Melissa Mayeux or Chelsea Baker (the knuckleballer in Florida) or Ghazaleh Sailors (the former D3 pitcher) or Sarah Hudek (the LHP who signed to play JUCO ball in Louisiana) or any other woman having every opportunity to pursue baseball as far as their talent and drive take them.
I think it does them a disservice to make them bear the mantle of potentially becoming the first woman to play MLB (even though all of these women I've named have handled the hype with grace and humor). And I think it does them no favors when articles exaggerate their accomplishments, competitive standing, and likelihood of achieving what has so far been an impossible dream.
No teenager who isn't already accomplishing the kinds of things that MLB prospects do in their teens needs the pressure of being held to the standard of reaching the majors.
What will it take for a woman to play in MLB?
Remembering that advancement in baseball is a game of attrition at every level, current averages suggest we will see a woman play MLB only after about 20 women get drafted and play in the minor leagues, which will happen only after about 200 women play D1 baseball, which will happen only after about 20,000 women play varsity high school baseball.
Maybe someone will emerge as a bolt out of the blue, but the odds are against it. In sports that are easily measured (track and field, swimming, etc.), the top women in the world generally post accomplishments about on par with the best 15 year old boys. I have no reason to believe the complex athleticism required to excel at baseball will make baseball more accessible to a trailblazer.
Enjoy watching them play. Root for them. Give them every opportunity to develop and compete. But don't lay the burden of reaching the majors on them.