Brrrr, you make me shiver. How can you even talk about "application" programming environment? It's JavaScript, its a Scripting-Language! Any use of it to create something like an application is an abuse. And "consistent" is anything else than what I expect from a script overriding every preference on my computer on how to use the human interface.
Well, there speaks the ingenieur, but I know, the whole world jumps on board... Its a hype, we'll see how this all ends.
Well, you are wrong. It would indeed be possible to implement office applications like Word, Excel, Powerpoint, etc. in the browser window using
only JavaScript/AJAX, CSS, HTML DOM, without any plug-ins. They would look and work exactly like those, and with a fast enough JS engine they would be as fast as the native counterparts. We might need some more improvements in HTML5 and AJAX, but they are all coming soon.
In fact some web applications would even be faster than the native applications because by using AJAX the server side computational power adds up to the client's performance.
What would we gain with all this? Ultimate platform independence. Reduced client side hardware cost. Improved security.
I said "would" but in fact I should have written "will". Because this is the future for sure. Even MS is starting to get into the web application business.
Surprisingly, even gaming is not out of question in the future of web applications. I'm not talking about the latest 3D rendering engines per se, but most simpler games that don't have such high performance needs can be easily implemented once SVG or CANVAS 3D gets properly implemented in HTML5.