Everything that is done with a platform dependent app can be done with a platform independent web app. I don't know what the best way out of this is but app stores were a step back. Your phone could have one app...a web browser and maybe a few utilities like a calculator, calendar, clock. Even these could be implemented as web apps running in the browser.
That’s more or less where browsers are (or are heading rapidly). It’s dumb and terrible and has all sorts of issues: but it’s also cheap and easy, and often that’s good enough.
So you can't have any platform differentiation and at the same time lose any cohesive, platform specific UI with known conventions.
Instead of two major mobile vendors we end up with one or best case scenario two major browsers from one or two tech companies with enough resources to to build and maintain them.
Or we could just have open standards like the web originally was and mostly still is. You can use the gmail web app from a wide range of browsers. Even Lynx in the console...It is not like you have to access a separate gmail web page for each browser you use. I don't get why people think web apps would need to lead to proprietary browser dependence. Not if they are coded for
open standards, like HTML, CSS, Javascript, etc.
