I think if Hingis can beef up that serve a little bit, and maybe serve-volley a bit more, she could keep up with the "big babes". Everyone says she needs to play a power game and hit the gym but I disagree - Hingis doesn't have the stature for it. Plus, she's too smart to be a baseliner.
As for Anna, I think once she wins her first title, the weakest part of her game will improve... her mentality. The talent is there, but the mentality is not. Once she can improve the mentality, she will be a legit contender at the major tournaments.