You make a fair point but it's one about the current state of apps rather than the future of apps. In the future phones will be more powerful and apps will do mostly the same stuff. In theory that should mean the apps will be faster.
Single-core performance is largely topping out. The gains are incremental at best.
Mobile SoCs have gone incredibly multi-core incredibly quickly (6-8 cores are common!). Meanwhile the web is incredibly bad at handling that. JavaScript code still has to fight with the GC for CPU time on the single thread they both occupy. WebWorkers are incredibly heavy & limited.
WebAssembly might have threads eventually (it's on their roadmap), but then how long until that happens and will the typical webapp ever even migrate to webasm?
Meanwhile CSS & DOM performance continues to be poor, so webapps are left in this awkward state of needing to re-write part of the browser.
Hardware isn't fixing any of this. It's been almost a decade of hardware not fixing this at this point.
The DOM is not slow, that is brain washing from React developpers to justify your VDOM.
Most Reactive app performance issue nowadays comes from library bloat loading, network saturation or data dependencies.
The main problem with the DOM is not the performance but the API. The DOM API is not appropriate anymore for a reactive usage with transactional reflows. And this triggers a lot of quirks damaging performance.
I'm comparing against native apps, not React VDOM vs. DOM. Direct fiddling of widget properties is common & perfectly fast in native apps, even when done naively. The same is not true of the DOM, especially with all its synchronous layout & style resolution foot-guns.