It has only been a couple of months since Samsung came out with the Galaxy A (2017) series and even though the refreshed series was launched after Android 7.0 Nougat came out, they came with Android 6.0.1 Marshmallow out of the box. Now that Samsung has released Android 7.0 Nougat for devices like the Galaxy S7, Galaxy Note 5 and Galaxy S6 Edge+ it can focus its attention on mid-range handsets like the new A series.
A model of the Galaxy A7 (2017) has appeared on a popular benchmarking website and the listing reveals that it was running Android 7.0 Nougat. We usually see such listings pop up whenever a major software update is in the pipeline for a supported device.
Even though the listing specifically mentions the Galaxy A7 (2017), it can reasonably be assumed that Samsung is also testing the Android 7.0 Nougat update for the Galaxy A3 (2017) and the Galaxy A5 (2017) as well.
Samsung hasn't confirmed as yet when the Galaxy A (2017) series is going to receive its Nougat update but it might take a couple of months before that happens.