Google is going to reintroduce the manual exposure control to their camera app in the near future, allowing users of Android 7.0 Nougat to access the function. For those that have been using the Android N Developer Preview, manual exposure control may not seem like a new thing and it isn't, technically. Google had already inserted manual exposure controls into the camera app with the first developer preview of Android N, but the feature ended up getting removed in a later release, so it's likely to be a welcomed addition to the stock camera app that comes on all of Google's Nexus devices especially for those who had been accustomed to using it once it was introduced in the first place. Alongside bringing this feature back, Google has also tweaked it a bit, as users will see the slider bar for adjusting the exposure manually when they tap on the screen to autofocus on a subject.
As it currently stands, the manual exposure control is not included in the camera app for users and there was no mention of when the update will drop, but it will be an update to the camera app. Since it was only introduced with the Android N Developer Preview though, it won't be available to users on previous versions of Android software. It's also entirely possible that Google may not end up pushing out the updated camera app until they release Android 7.0 Nougat since it's going to be a Nougat specific feature.
If that's the case, it's quite likely that users will end up seeing the new version of the camera app, a public release of Android 7.0 Nougat, and two new Nexus devices all at the same time, as new versions of Android tend to be released alongside new Android hardware. The reintroduction of the manual exposure controls also wouldn't be the only change coming to camera app as just yesterday it was rumored that Google may be looking to add in some more grid options for users. With new grid options and manual exposure controls seemingly on their way soon, it's possible that Google could be adding in some other feature changes or improvements as well.