Making an Adventure Path for Shadow World is something that has come up a few times. One problem with doing so is having enough time/ability to create one. So, how about if a number of people try making one?
Possibly the best place to start would be by using one of the following modules:
Demons of the Burning Night
Gethaena Underearth Emer
Islands of the Oracle
Kingdom of the Desert Jewel
Quellbourne: Land of the Silver Mist
These can all, as far as I know, be modified by GCP without any problems. Another option would be The Iron Wind. Kingdom of the Desert Jewel would likely be the most difficult, due to Alliance influence in the general area.
Should one be successfully modified into an AP, it would then need to be seen if GCP would be interested in publishing it. Actually, it would be helpful to know this upfront.
This would be quite a major piece of work, even for several people. Making an AP at about the standard Paizo size would mean expanding the content from an existing module manyfold - such as around six times.