Yeah but we've seen that smaller girls can make it. she's only 15 so hopefully she has a couple years to grow, she's about 5'4 right now.
Well girls tend to peak in their growth earlier than boys, so she would want to start growing quickly.
I don't know whether we've seen smaller girls make it. Other than Henin, there hasn't really been any small girls doing too much at the top of the game since Hingis. The odd one here and there has popped up briefly, but they are being overwhelmed by the bigger girls.