Platform dependent apps will be here as long as the platforms will have different functionalities. And I hope that innovation in hardware space will not stall.
Found a web developer.
Not really. I'm building apps on Web/iOS/Android. And it sucks writing the same code for three different APIs.
It's very intellectually unfulfilling work.
Write command line apps in C. The only platform that can't run them is iOS.
iOS can run Objective-C which is a superset of C, you can run the code natively and use Objective-C to display it.
iOS lacks fork and kills your app if it doesn't yeild for some number of milliseconds. It also lacks a shell and a video terminal emulator which are kind of nice to have for these sorts of apps.
I have high hopes on WebAssembly. It's not the current intention but it could become a universal virtual machine.
OP author here; in another blog post I explored the growth in questions about some cross-platform solutions. Ionic (now Ionic2) has been growing quickly, and React Native is among the fastest growing tags on the site. So you may get your wish!