JavaScript will start to predominate in 2006. Web pages will include much more JavaScript behaviour - from personalized home pages to giant corporate web sites. Flash will also rise in usage. A major search engine will get all AJAX-y.
JavaScript will become mainstream. People will get over their aversion to Flash. Examples of what will become more common: Kayak - travel search engine (JavaScript) and Etsy - find handmade goods (Flash)
In other words, the days of the static web page are over.
The downsides of this AJAX explosion?
The upside is that the web user experience gets faster and more interactive.