I don't believe that Anna Kournikova is seriously injured anymore and it's clear by the number of exhibitions she has played over the past two years that she could at least mount a comeback in doubles. But she's not yet interested in testing herself against the elite anymore, which is why she bailed out of a singles match against Steffi Graf in World TeamTennis last summer.
If she were to put back on 10 pounds of muscle and rededicated herself, she could make a drive at the top-20. She was that good. I also believe that had she beaten Anna Smashnova in the final of Polo Open back in September 2002 that she would have never retired.
Getting the "no title" monkey off her back would have been huge to Anna, even though she consistently said that it wasn't that big of a deal. For someone who had as many top-10 wins as she did, it became a very big deal that she couldn't string four wins in a row together at Tier II events.
The word has it that she did marry singer Enrique Iglesias and still earns close to $10 million a year in endorsements and appearances, thanks to her brilliant agent, Octagon's Phil de Picciotto ... and her looks.
Financially, Anna has no reason to return to the tour, but the feeling here is that she will during the next year in doubles, and very likely partner with Martina Hingis.