It's not. And, native apps are likely going to make even more ground. I realize this runs against popular opinion, that webapps are some sort of inevitable future to replace native apps almost in their entirety, but we will see.
Maybe you won't reach the same quality on iOS and Android as you would with native apps, but for smaller teams this can be a huge time saver, especially in the early stages of a project.
So in a lot of cases it's not so much "web app" vs "native app", as "web app" vs "no app".
I'm just realizing that we may not be innovating as we think we'd like. Basically, we found a way to force the browser to act like native desktop apps but without the security and power of native apps. In the process, generating a great amount of technical barrier and debt. Businesses will still use a java swing desktop app if they paid millions for it in the 90s. We'll still work on desktop IDE's to code our stuff.
Another discussion here would be how "mobile" is going to replace desktop apps. This is simply not true. Lot of important work goes on with a mouse and keyboard behind a monitor. I just don't buy reinventing the wheel. Sure it works for activities centered around the mobile phone mainly communication applications and social apps but i don't see how it can cause disruption.
I have a feeling one of these days, we'll see a major correction in how we perceive our point in time as being the best possible state and we'll see more or less the return of old ideas, the true and tested technologies get more attention they truly deserve.