Funnily enough, I actually wrote this post because if you had asked me about cross platform web apps 6 months ago I would have said the exact same thing you just said.
In 2014 I'd started an app using Ionic and actually ended up abandoning it and it killed the project. I was so frustrated. That's why I was shocked with this app (and yes it is small and pretty simple) actually worked really nicely being a react app bundled into a webview. It's crazy, I was just shocked.
Made me realize that cross platform web apps are a hell of a lot more capable today than I had thought.
And sure, maybe claiming native apps will die eventually is a pretty bold claim... But technology moves. And the direction it's going now, is in the direction of browsers becoming faster and more capable at a greater rate than user's desire for more elaborate UIs. Visual Basic and Java used to be the hottest tech you could have on your resume. Who knows what will be old fashioned and out of date in the future.
I don't normally make bold claims but I think I'll stick with this one and maybe in 5-10 years I can fish out this blog post to see if I'm right or not.