A patent recently granted to Microsoft points to an interesting new set of touch capabilities for the Surface Pen. As detailed in a patent that was first filed by in 2016 and was recently granted by the US Patent and Trademark Office, (via MSPU), Microsoft details a method for making the Surface Pen's retention clip touch-sensitive.
As described in the patent, this could open up new ways of interacting with a PC connected to the pen. The most obvious use would be to let the clip to act like a mouse's scroll wheel, allowing a user to scroll up and down a page or image with a swipe. That could come in handy if you're trying to use the pen as your only input device, for whatever reason.
The patent also details a method for implementing a power saving mode with the Surface Pen by using the clip as a way to switch the stylus out of power saving mode when it detects touch.
It's worth noting that patents are filed all of the time for tech and ideas that never see the light of day. There's no guarantee that a touch-sensitive retention clip will make its way to a future Surface Pen, but it's certainly an interesting idea that could add some handy features to the Surface Pen.