The rumored OnePlus 3S might actually be called the OnePlus 3T

Based on previous rumors, the OnePlus 3T might come with slightly improved internal hardware. For one, the Qualcomm Snapdragon 820 chipset that powers the current-gen OnePlus 3 is said to be updated to the latest Snapdragon 821 chipset. 

As the model numbers imply, users shouldn't expect to see a big performance difference between the SD820 and the SD821, although the improvements that the new chip does feature, such as 10% more processing power and better power consumption ratios are not be ignored. Furthermore, the OnePlus 3T is expected to run Android 7.0 Nougat out of the box.

Edit: as one of our readers suggested, the 3T moniker could easily stand for 3 Turbo. At the moment, however, this is nothing but pure speculation.

Previous rumors had suggested that the new OnePlus 3 version will come with an IPS display. In the meantime, however, OnePlus CEO Carl Pei has confirmed that his company's future handsets will all make use of the same type of Optic AMOLED display as the OnePus 3.