Motorola has started sending surveys for a software soak test to owners of the Moto X Pure Edition (2015), which is basically the US version of the Moto X Style sold internationally. Unfortunately the company isn't saying what exact firmware update is the one that the soak test will be sent out for. However, it seems pretty likely that we're talking about Android 6.0 Marshmallow, since no other new versions of the OS have come out from the time the phone was launched. Soak tests are sent out by Motorola to people who sign up for them in order to make sure that its over-the-air rollouts are going to work flawlessly when a new update is then released for every device out there. They are also a good way to spot last minute bugs in the wild. Of course, this could be nothing more than a security patch of some sort, but obviously given Motorola's history of quick Android updates (especially for its unlocked high-end devices) there's also a possibility that it is indeed the first step in pushing out a Marshmallow release for the Moto X Pure...
Source: http://www.gsmarena.com/latest_moto_x_pure_edition_soak_test_starts_soon_could_be_android_60-news-14408.php