This is exciting stuff for themes and theme end users. I am looking forward to the release. My two cents on why this won't put anyone out of business:

It eventually comes back to "design". Think about it, these tools give everyone the chance to design but that doesn't equate to everyone designing well. In fact, I tend to see the opposite effect. There will always be a market for a well designed theme that meets a need out of the box.

The other issue is speed and code bloat. It is impossible to build an entire WYSIWYG drag and drop theme editor on top of WordPress without introducing some markup bloat on the front end. Think about using a tool like Dreamweaver versus professionally hand coding an HTML template from scratch. The finished product may look similar to the end user but the code tells a different story.