Yesterday I read a post titled “How Apple Killed The Future Of Search” , in summary the post speak of how Apple’s iPhone/Touch/iPod/iPad groups of specific applications that link to web site applications are eliminating portions of Google’s traffic and that this trend will continue. Think of if you use an application for Facebook or Twitter, are you going to hit Google for anything in that process? My guess is that you won’t unless somewhere there is a link buried to something on Google.
This logic actually sounds like it is indeed what the next evolution of the web will turn into. There will be destinations that are really applications around specific topics. This specialization of the interface, site, application, and the user base will make it far more compelling to visit and will reduce people having to use a search engine to find the things that interest them. As time progresses, the need to do general search will diminish (although it will never be completely gone).
So, yes, I think that after enough time, Web Applications will make Google Search a tiny portion of what people do and care about (which is really where it should be anyway).
A final parting note: I’m not saying that Google will be killed, simply that SEARCH will not be the all powerful thing that it is today for Google.