I'm positive she'd play much, much better than we should expect from a 43 year old, and I'm sure she could beat a lot of players. But, she still is 43. I don't think she'd be dominant like she was. It sure would be interesting to see her play for a year on the tour.
It would be a fantastic reality show - "The Comeback" starring Steffi Graf, Martina Hingis, Lindsay Davenport, and Martina Navratilova (maybe doubles only for Martina, unless she's game for singles). Basically, we follow these 4 players as they try to navigate today's tennis tour. Whoever posts the best results wins the prize!! (of course, they're all wealthy, so what would really motivate them).
Graf was injured all the time when she played.
Out of those 4, she'd be be most likely to break down. much like Nadal, she was incapable of not training ridiculous amounts of hours in order to compete at a high level. Do you think her footwork is just there stepping out of bed? It takes a crazy amount of work.
If she attempted a Kimiko Date, wouldn't be surprised to see her retire in her 1st or 2nd match due to injury. No way could her body take a full year on tour (Date is a childless 43 year old, who played way less career matches than Graf, not in the same ball park as far as miles on the body. and she ran marathons for years before deciding to come back)
weird that so many think that winning pro tennis matches is mainly about ability or talent. Roddick was top 20 last year & retired because he was sick of being in pain all the time. Why the hell would any of those women want to put their body through hell again, its probably not their idea of fun. Now an exo once in a while(without having to worry about how you feel the next match) those are fun.