Need more information. Which tournaments, surfaces, etc. If she were to play only the biggest tourneys, you could probably count her wins on one hand, with fingers to spare. But if she played lower tier events, on surfaces friendly to her game, she could pick up a handful of wins. The 15 tournament limit would leave almost no margin for error, though. A tough draw means one and done, with no chance to make up for it later.
As far as her fitness, the recovery would be the most critical thing. I remember Nolan Ryan's comments. He was able to pitch no-hitters into his mid 40's because he, like Martina, was in extraordinary shape. He said he was as fit at 45 as he was much earlier in his career. But, he said he didn't recover as well. Any particularly taxing efforts hung on him longer.
I think it would be the same for Martina. She has been, hands down, the fittest woman to ever play the sport. At 36, she pulled a "double-Ai", by having to play 2 singles and 2 doubles matches in the same day TWICE in a row in the same tournament. And still managed to reach the semis of her next tourney. However, 47 is a long way from 36. I could see her getting through 2 singles matches in one day, but it will take a toll on her in the following round. (That's assuming she'd be able to win both matches, which is another issue.) Her age would play a double factor, in that not only would her recovery time be adversely affected, but she's also a bit slower and not as powerful, and thus would have to work harder for each win.
If she were to schedule herself to maximize her chances, I could see a definite top 100 ranking. Top 50 would depend on her draws. But she could get high enough for DE into slams. (Maybe she doesn't want Amy to catch her.)