Keep in mind DHH is working on an email app, it makes sense he sees native as the default option for that over pushing everything through the web when the barrier to entry lowered dramatically.
Hotwire is not explicitly a cross-platform concept. It's primarily a way to build web apps in the browser which is not going away any time soon. The only difference is in 2026 you're just more likely to vibecode a native mobile app than build a web/React Native version. Likewise you may build a native Desktop version instead of an Electron wrapper.
So even if we can generate an app easily now, is that a wise choice for every business?
Server side rendering makes sense for mostly static content, but for web applications, a front end framework and a back-end API are a much better match.