It's been talked about for a while now, but Intel is slowly embedding AC WIFI to their processors. The first partially ones will get supported by Cannon Lake & Gemini Lake. 

Intel has unveiled the Wireless 9560 (embedded on the processor side it is called 9520), this will be the first product with partially integrated WiFi. So it is not 100% integrated just yet, but many primary functions have been migrated into the CPU or the SoC or the PCH, which saves costs, space and energy reports computerbase. 

An add-in module then can connect directly towards the processor, and that leaves out utilization of costly PCIe lanes. By moving the primary connections into the processor, over time it is expected that the WIFI solution will get cheaper.  So basically the WLAN module no longer needs to be powered by a PCIe lane or USB, since the addressing is already done in the CPU or the SoC or chipset. The wireless AC-9560 adapter is therefore only a "companion module" for AC WIFI  functionality, without it WIFI obviously does not work. 

In addition to the regular M.2 2230 format, the bridge chip can also be obtained as 12 by 16 mm package module, saving more physical space on the PCB. 

Intel Makes Wireless AC 9560 A Bit More Embedded