All software can update. There is nothing fundamentally different between a web apps' ability to update and a desktop applications' ability to update. If you need any proof of this, just look at Chrome.
Once you run software on your computer, if that software can connect to the internet, it can update itself!
there is something fundamentally different, you can choose not to update a native appp, you can also choose to run an old verion. you can also continue a native app if the creator decides its not worthwhile, or google buys them out
My point is that there is nothing* preventing any native app from including code to update itself. Over time, I believe that more and more native apps will do this. For example, Firefox is moving in that direction now.
* Except for in the case of iOS. Apple has a policy that apps are not allowed to update themselves. But there's still no technical limitation.
Right so we're discussing the reality of the situation, which is that web apps would have no choice but to force update (as they would be run server-side and hence the client wouldn't have a choice) and that native apps could be possibly, but aren't.
Once you run software on your computer, if that software can connect to the internet, it can update itself!