Today, T-Mobile published a list of its own carrier version Samsung devices that will be getting the OTA at some point. It is preliminary and more entries could be added in the future, but currently it includes the following handsets:
• Samsung Galaxy S6
• Samsung Galaxy S6 edge
• Samsung Galaxy S6 edge+
• Samsung Galaxy S7
• Samsung Galaxy S7 edge
• Samsung Galaxy Note 5
• Samsung Galaxy Note 7
Frankly, this fits perfectly with Samsung's track record of typically supporting its flagship models through two major updates or roughly two years. Of course, there have been exceptions in the past and as we already mentioned, the list can be updated in the future. However, owners of said smartphones from T-Mobile can already rest assured that they will be enjoying Nougat in the future. As for timing, well, that is a whole different story.
Given that we haven't heard anything about ongoing testing or any other related leaks, it might be two to three months still, before builds start seeding. Unfortunately, that is simply the way the mobile support chain currently operates, especially for Samsung devices with their heavily-modified Android builds.
Last, but not least, it is also worth mentioning that T-Mobile has the HTC One M9 and HTC 10 on its official waiting list for Nougat as well. They are likely in the same boat time-wise as their Samsung siblings.