It'll probably depend on how much she needs the money.
Holly Halston "retired" 3 or 4 times during her career, and she always came back when she was running short on dough.
I'd agree with this. At this point, only money is the driving force for her and her career. Short of giving us a DP scene there isn't much more for her to do in the industry.
Based on her descriptions of the injuries and surgeries she had, if she's at all self-conscious about her body I don't know how the scarring will appear in HD and she may not want people to see that.
Also, let's be honest, what made her so amazing was her flexibility and mobility during sex. She could do some stuff most can't. And I have a hard time imagining her still being able to do some of that based on the injuries she sustained. Hell, I'd hate to see her even try and risk injury or put herself through pain just to live up to her own performance standards.