Nice analysis, but only half of the story. As pointed out in the comments, you can make thick or thin clients in both native and HTML5. The issue is rather the one about lowest common denominator. HTML5 aims at working in very varied "runtime environment", where standards are bendable, bugs are rife and feature support a few years behind what native could muster. HTML5 is more difficult, and does not have all the tools, of the native environment. So the question is rather - will HTML5 develop faster than native and thereby be on par with it, or will it always be the straggler?