We shouldn’t think of “the web” as only what renders in web browsers. We should think of the web as anything transmitted using HTTP and HTTPS. Apps and websites are peers, not competitors. They’re all just clients to the same services.
Perhaps it's not HTTP and back end web that is in danger, but it's the front end that's in danger.
For whatever reason I don't feel particularly worried for the web, even front end. It feels like a safe long-term bet.