I hope to god that card slots and USB3/ThunderBolt connections don't disappear just yet!
Olympus have done a reasonable job on their WiFi implementation, but the rest are still only performing during 'amateur hour'. Maybe the new foolography WiFi initiative will bear fruit for Canon & Nikon users?
Canon has been ahead of Nikon in terms of tethering even with the cable. My friend pro photogs who use Canon seem to be using wifi pretty efficiently to show each shot to the clients on iPads. Of course, a USB card reader should be much more efficient when transferring RAW data. SD card aside, both XQD and CFast are too obscure for their card readers to be on the notebook PCs or Macs. Also, the card socket should prevent the notebook from being made thinner. So, the pro photogs and enthusiasts would need to rely on wifi/bluetooth more than the amateurs and beginners.