Currently Angular uses Zone.js to make DOM change detection on browsers events, async XHR etc.
There are quite few problems:
Zero progress on pushing it to browsers as a standard. On the other hand Proxy is already supported by most browsers.
There is no way to monkey patch async/await after they are fully supported on all browsers. Currently Zone.js is working just because async/await is converted to generators and promises. In the feature this is going to be a problem.
ChangeDetectionStrategy, Zone.runOutsideAngular are needed just because angular is not smart enough.
Describe the solution you'd like
Mobx and Vue showed that observable based reactive change detection is a powerful and smart thing to do. Mobx 5 introduced Proxy based observables which overcomes problems with observing dynamically added properties. The only problem is that it is not supported on IE11 as it's not polyfillable. I propose that Angular should also use Proxy and observer pattern to do change detection.
we have looked into it, and decided against Proxy. There are several issues with object identity and deep watching which we don't like. So I am going to close this as we don't have any plans to take the framework that direction.