Why do you consider it "ideal native?"

What was a good case for a desktop app even two years ago works fine on the web today (e.g., WebGL stuff, canvas-based apps.) Chances are this will be even more true 1-2 years from now (when a product like this would have become quite polished.)

A web app can offer cheap distribution, a more iterative development cycle, split testing, more monetization flexibility, piracy protection, a larger market, immunity from platform trends, and virality (share interactive designs even with stakeholders who haven't downloaded or bought a large creative application).