JavaScript is a pretty crazy beast that's hard to predict because there are so many interested parties, and so many things that can influence it. Not just leaders trying to shape the language, but everyone working on implementations of JavaScript can change it by discovering new ways to unlock performance for specific patterns previously though impossible, and these new tricks unlock new possibilities of the languages (simple example: JITs rocked the dynamic lang world).
10 years is really long, so I suspect there will be at least 1 more big revolution like React on the frontend space. I think JavaScript is going to continue to lead the UI space, and possible invent even better ways to build it. I doubt this will happen, but there's a small change the JS will even get immutable data structures, which will change quite a lot and even strengthen the model that React uses to build UIs. If so the component model with immutable data may see some platform support. Possibly even native virtual dom in the browser.
I do think we'll realistically start seeing user-land layout implementations in the next 10 years. WebAssembly has crazy potential to unlock a lot of things, stuff like off-thread layout and rendering implementations, so the web becomes a simple low-level platform like an operating system. If this happens, maybe we'll start seeing JavaScript accessibility APIs to keep your apps accessible.