Apple has been granted a patent that allows it to use a future edition of the Apple Pencil with the Magic Trackpad. That combination could potentially allow users to draw on their Mac without the need for an extra peripheral like a Wacom tablet.
The patent, which Apple applied for back in 2014, describes a much more powerful version of the Apple Pencil than the first generation model. Support for in-air gestures to change slides in apps like Keynote and turn pages in Pages, and the ability to operate as a joystick for games are both described in the patent application.
As with all patents, there is no guarantee that Apple will add any of these features to future products. But given the multitude of applications this could work for, I'd bet these features are more likely than most to end up in the Apple Pencil sometime down the road, hopefully in the near future.