Sony could be making a DualShock 4 PC adapter
It's all speculation at this point.
Sony has filed a certification for a wireless bluetooth adaptor, and the smart money is on DualShock 4 PC adapter.
DualShockers spotted the filing, and the suggestion that it's controller-related stems from the letter Z in the first half of the code, that's "normally associated with controllers."
Sony's Shuhei Yoshida has discussed PS4 hardware being supported on PC in relation to PSVR, saying that, "[the] Playstation 4 shares a lot of its internals with PCs, the possibility is there," so controller support is feasible.
Do you think this is what the filing refers to, or do you have any other ideas? Let us know in the comments.