I think a Professional version of the book with a real world example would be an excellent book. Who knows what the future will bring. =-)
There is a new book coming out in a few weeks that does something quite similar to your suggestion. Rather than a single example, it is comprised of multiple scenarios written by 16 SharePoint MVPs. The other author of this book, Shane Perran, contributed to one of the chapters in fact.
You can learn more on that book here:
Thanks for your great ideas!
MVP - Microsoft Office SharePoint Server