AJAX applications are far from replacing desktop office apps. So is Flash by the way.
Several projects are trying to prove the opposite. I still think that it will not happen.
Rich interfaces were left to Flash at that time. As the Flash Player resides in the browser as a plug-in and operates as a natively compiled program for the platform it is run on, it provides more speed and is not only fairly dependent on browser restrictions. Additionally it is optimized for multimedia operation which made it first choice for complex navigation.
There are a few points that keep AJAX apps from taking over. They mainly go together with arguments against Flash.
- We are still caught in a browser. Ordinary web apps sit — by definition, of course — in a web browser. There are no means for accessing the local storage — which is initially a good thing. But when it comes to web apps you need to do all this up- and downloading to use these apps. Or you store everything at their server.
- We are still caught in a browser. This is also a problem of user interface. "Normal" users have slowly adopted a different way of using interfaces when surfing inside a browser (single click vs. double click). With new interfaces we challenge them to start using web apps in another way once again. We should think about that thoroughly.
- Web apps want your data. (see What is Web 2.0 by Tim O'Reilly) When using web applications you need to trust that app and give them all your data. Also for security reasons there is no chance to properly store the data on the client side. But even if there was, the web app would already have all your data anyway — as it needs it for processing it.
- Flash is a plugin. On the one hand it's a good thing. We have more CPU power. On the other hand it just does not feel right. I cannot use the browser's find function. Brr.
For these reasons I stick to my opinion that most of the web based office apps we see now are just a proof of concept. In near future they will not replace real office apps.
We also need to find methods to be able to effectively share data with our desktop computer. The current solutions I know are far from usable and prevent any ordinary user from getting into such projects.
All in all I am far from being against AJAX apps. But we need to keep the focus on apps where the technique can be applied in a useful way. I see them in the fields of collaboration and communication.