Highly unpopular opinion: by 2030, React will probably go the way of jQuery (i.e. a highly popular library that was once considered almost an "industry standard", but later ended up in a graveyard of projects, tutorials and articles).

Difficult to say what the replacement will be, but I suspect it will be some form of plain JS + MVVM architecture, with a VM (view model) with two-way bindings, possibly natively part of the DOM, or even the DOM itself being optimised and async-ed to a point where virtual DOM diffing and similar approaches are obsolete, and an M (model) basically providing a client-side interface for the server API with some level of local caching, and providing an event listener interface for the VM to update itself. You may recognise some of these features from much older libraries, but I think a lot of them will be available natively in browsers (hopefully standardised, or in a darker timeline, fragmented between major browser vendors).

Another possibility is HTMX-like partial updates getting more native browser support, essentially blurring the line between multi-page applications and SPAs.