At which point, the question becomes, "why is this a website?" if you're building an application, usually languages like C#, Objective-C, etc offer far more powerful tools for making an application.
Then surely all the effort being put into make browsers not browsers would be better directed towards solving those goals, without bastardising the web?
I always thought that the SPA crowd would settle on a custom content-type to handle web apps. That way they aren't hamstrung by the limitations of HTML and web pages and can really do things right by web apps.
