I believe that when you go through an instance portal you are transported to an entirely instanced zone/terrrian along with the instace itself. Please dont call me crazy for posting this but i have examples that support this.
1. When using WoWMapViewer I compared the uninstanced Shadowfang Keep and surrounding lands to what I call "the instanced version". There where major differences They are as follows:
2. Also if you compare instanced deadmines and uninstanced deadmines and both of thier surrounding areas there are major differences. I will not list those differences because I am in a really lazy mood tonight so look for yourself.
- There were no buildings where ambermill is supposed to be
- The ocean near the keep was much shallower than in the uninstaned area.
If all of this is true than this could open up many new doors when it comes to expioting instances. I welcome any comments on this matter after all it is just a theory.