If You See a Stylus, They Blew It. is a common refrain at Daring Fireball. And it’s true that Jobs did say exactly that, but that’s not important right now. I’ll go out on limb and bet that an iOS device will support some sort of stylus input within three to five years.

The stylus will never be the primary input device and the interface will never be designed around the precision that it affords but, in a few years, I believe that the sensors embedded into the iPad, and possibly the iPhone, will enable a greater input fidelity through the support of stylus style devices. Touch events will expose the touch radius they already track but they’ll also expose the pressure, angle and device identifier. For a finger the device identifier will be nil, the pressure will be a constant, the angle will be a constant and the touch radius may be exposed in device specific units. For a stylus device the device identifier will represent a unique nib for the pen tip or eraser of each stylus pen, pressure and angle will be determined just as they are now when using a Wacom tablet on a Mac. I know for a fact that major enterprise customers in the graphics field already rely upon the touch radius that isn’t yet exposed publicly. To expand the use cases of iOS Apple will need to support higher-fidelity input.

That’s not to say that iOS will ever require a stylus type device. I’m simply arguing that within a few years iOS devices are likely to support input mechanisms that afford a far greater fidelity than simple touch input.

I’ll go on the record as betting John Gruber that within five years we’ll see an iOS device that supports a stylus natively, but not as a necessity. I see the stylus starting as a thirty dollar accessory targeted at markets that require the additional fidelity.

The brush has been around since the earliest cave paintings; fidelity of input will become a killer feature.