There's a lot of buzz generated after the releases of Google Gears and Adobe Integrated Runtime (AIR). This brings up thoughts on the so common pendulum effect operating in broad levels of life and evolution. Particularly in the computing sphere there are subjects like centralized versus distributed, web versus desktop, etc. that keep going back and forth at different heights of the spiral, meaning evolved versions of one or the other keep coming back.
My take on the off-line buzz and the desktop comeback is that the conclusion is wrong. Off-line is great and is going to be a very important step on evolution as far as allowing mobile computer systems to move across networks without any awareness of the disconnection as well as to handle connectivity intermissions but not to replace in any way the web. As an improvement to the web experience off-line apps are a must, as a replacement of the web experience I don't see it happening with the exception of a few applications.
To believe that the desktop apps will come back sounds to me similar to thinking that there will be a come back of public phone cabins and land lines because cell phones sometime run out of battery ...
Users need connectivity, if they're not "online" something is wrong and they can't work/use the computer in a healthy way. No "off-line" transparency will give users the online feeling. So, for a small period of time, if I'm not online maybe I don't even realize and I keep going happily through my computer usage, but as soon as I start trying to interact or I don't get the amount of emails/contacts I'm used to, the whole off-line experience will be quickly evident and the discomfort will be there. It's almost as subtle as a psychologically effect.
Anyway, connectedness is the way the world is going, technology will push connectivity and it'll be more and more exceptional the instants when we're off-line. Handling the off-line instants is a great feature but won't bring back desktop apps to where they were, in my humble opinion.