This looks like a very promising option for the future of editing WordPress sites. I think the biggest issue into the future might be the interaction between the thousands of existing themes and plugins. If this does take off, one would hope to see it be potentially enforced at the core level of WordPress. This way they might be able to implement some mechanism to make future themes and plugins support this type of framework. I myself often have multiple windows open when managing a site as it helps to easy the workflow of my edits or linking, etc. Having a framework that could make this process even easier then it already is would be welcomed by me.