There was never a concept of State-as-first-class citizen for UIs.
And there as never a cohesive multi-screen layout engine story, like we have now with flexbox (via RN and RNW).
So in my view, the data binding via explicit state-management paradigm that React introduced -- will survive for decades, and will be copied to other programming environments.
Same, probably for flexbox as a layout management model...
Although, there, I wish that it would be more 'typefull' where various incompatible layouts could be flagged as errors or warnings at compile time.
Perhaps (and may be this is is far fetched) with the advancements in practical category theory, compute power (including at compile time) -- we should be able to do 'shape' management as algebraic concepts -- where layout engines, should be able to treat layout definitions as composeable, multi-variable functions.
WRT javascript vs C#, I was just noting, that, in my view C# is just a much better language, and I wish it would have been a de-facto web-standard and not javascript.
This way something like React, would not have been conceived in javascript.
You're at least a couple of decades late, there, and the other way around: instead of `Winuser.h`, it's `react.js`.