Michelle...her jumps look bigger this season (despite the missing loop) and reports say that she has been practicing a 3/3, wouldn't put it past her to try it at Worlds. Her spins at nationals also looked faster than earlier this season.
Irina...has been AMAZING and beautiful this year. She has improved her artistry a lot and is skating with amazing passion. She has also been skating under COP all year and has really worked out a good program for her ( for example she is in a bielmann position on her spiral sequence which looks great for her and also racks up the points)
Shizuka...probably not a major threat to defend her title, has had a tough year with illness and injury and I don't feel like she has connected with her music this year. She also has not beat Irina this year.
Joannie...if she skates like she did at nationals could be a surprise contender, I wouldn't count her out but in order for her to beat the above skaters she will need to be close to perfect and they will probably need to make a few mistakes because she isn't as good in other elements of her skating.
Cynthia...has had problems this year with nerves and fear. She has seemed really intimidated skating with the top senior level skaters and this has really affected her skating. Even at Canadian Nationals (which she won last year) she was a mess. I give her one more year of experience before I think she'll be able to contend.
Miki...has good jumps but not good enough artistry and shaky spirals. It would be an upset if she were to win.
The interesting thing about COP is that it somewhat takes away the surprise factor. For the skaters who have already skated under it this year we already have an idea of the range they will probably score in. An upset will probably only happen if there are major falls from the top ladies which will open the door for other girls who may skate clean programs.
I really hate to make predictions...but that's my two cents worth