Samsung has already started targeting Android 7.1, rather than 7.0 with their latest update of Samsung Health and Samsung Game Tuner. Both the applications are only supported on Samsung phones, leading to the theory that the Android 7.1 Nougat update is currently under testing.
The recently announced Samsung Galaxy S8 comes with Android 7.0 Nougat out-of-the-box and Android 7.1 would be a welcome move, as the inclusion of the almost a year old Android 7.0 was one of the Galaxy S8's biggest disappointments.
Samsung has already started rolling out Android 7.0 Nougat update to the Samsung Galaxy S7, S7 edge, Galaxy S6, S6 edge and Note 5. So, these devices are on the top of the list which are likely to get Android 7.1 Nougat.