It never fails that Google shows off something we think is pretty cool when they give us details about what the next Android version can do, then the people who make the phones don't include it. There is always that one thing. But it won't be the direct reply feature in Android 7 Nougat because Google explicitly says it has to stay.

Android Police noticed a line in the latest Compatibility Definition Document that not only reinforces an existing rule that managed API interfaces can't be changed but explicitly mentions notifications by name.

Handheld device implementations MUST support the behaviors of updating, removing, replying to, and bundling notifications as described in this section.

This means that the folks who make your phone have to include the bundled notifications feature as well as inline and direct replies if they want access to Google Play and all the other Google services. Peeking — think of that as a smart pop-up if you're not familiar with the term — and bundled or inline conversations in peek cards isn't addressed, so that's still going to be up to the manufacturers and app developers to support. As it should be.

Android 7.0: Better and more interactive notifications