Sure she can. Will she, probably not. As I said in another thread the womens French Open is a total crapshoot these days. There is no one specific player who has more than 20% shot to win probably. However she is probably one of only about 4 women with a 10% chance or better.
However as others have noted Serena must lose before they play for her to have any chance. Sharapova and Serena play there is only one possible outcome, especialy in a slam, and it doesnt matter where or when it is. The good news for her is it looks like they will be the 1st and 2nd seeds and cant meet until the final, increasing the likelihood they wont even play as one or both might well lose before then.