I think ember will stick around. I even think it'll overtake Angular one day since it has a better dev/upgrade experience. I don't think it'll ever hit mass appeal, partially because it's quite a niche cookie cutter and the frontend world seems to value flexibility above all else.
I have high hopes for Glimmer[1] though as something that can compete with other view libraries and/or frameworks. I'm especially glad that Glimmer diverges from the Ember brand a bit, because there seems to be a lot of outdated (mis)conceptions about Ember from older versions.
I personally feel productive with Ember, but the custom object models and getters and setters for everything are a bit of a turn off, especially after working on an Angular project recently with typescript support. Mobx, for instance, seems to be able to accomplish similar things as Ember but without the custom object model and getters/setters.
[1] For those wondering, Glimmer is Ember's next iteration of view layer and rendering engine, pulled out into a separate library. It's built from the ground up (and so isn't subject to backwards compatibility with Ember just yet), uses typescript, is component based, and it compiles down to op-codes that are used to update the DOM instead of DOM-diffing. http://glimmerjs.com/
