What the author doesn't mention is that apps have become increasingly easier to write as time has gone on. Not only do we have better native languages that you can write apps with (Swift and Kotlin) but we have incredible cross-platform tools as well in the forms of Xamarin and React-Native.

I've personally been working with React-Native over the past year and it's just as easy as writing React code for the web (if you're using expo), once people understand this it'll only be a matter of time before web-dev teams adopt it. Historically the problems with app development is that it was a lot harder than web development and often required you to learn a new language and framework in order to get anything functional, this is no longer the case.

I'd actually argue that there will be more apps going into the future as the technology needed to build them simplifies.