Changing the name of the chipset to 850 may be dictated by the desire to emphasize in the name of the x50 - the 5G network.
The processor will be installed in laptops and tablets. By the way, HP and ASUS are currently working intensively on standalone laptops that will use the latest Qualcomm processors. This once again proves that the products of this segment are quite in demand.
Most likely, Snapdragon 850 will be announced at the end of 2018.