Yes, it is something that is being worked on.
Ultimately, every resource will return an etag. As a client, if you make a request and supply an etag that you received previously, then the api will immediately tell you if the resource hasn't changed, with no body obviously.
If it has changed, the resource will be returned, of course with a new etag.
This handling would be particularly important for bandwidth reduction scenarios, such as mobile.
We're just not quite there yet with the implementation, but was included in our internal design guideline for our new API platform, which is why you see it (mostly) included.