I don't see a large movement to immutable data structures on the horizon in JS. I can appreciate the performance implications in Om, and would be interested in using React + Mori to the same end, but I'm not sure that it would keep me from having mutable data structures to represent most of my application state.
There are so many now-solved problems in JS MVCs that were a complete trainwreck several years ago - client-side routing, sanely managing data, and intelligently organizing your code base - that all assume mutable data structures and traditional object-oriented paradigms.
This might be the future of ClojureScript (in fact, it should be the future of CLJS, as it's much more elegant than any other view solution I've seen for it), and functional data structures may be a clever way to optimize the DOM, but this certainly doesn't seem like the future of JavaScript to me.