Not to dash any dreams here...
But... I believe those are slide-pads.. which I 'think' are some sort of flat resistor. I think the X and Y axis are combined into one single value reading. (similar to a drawing tablet)
Hacking these may not be easy, unless you have some sort of hardware encoder. Not sure.
Also, even when using mini-pots, Im pretty sure that the travel is still the same as a large pot. Meaning, you would still need to use gearing to have the correct resolution.
Making a Yoke full size is challenging enough... but making a mini yoke would be even more difficult. It has to be durable enough to widthstand a slamming... but, smaller gears means smaller & weaker diameter drive tubes.
Also, with smaller gears, means smaller teeth... which means that tolerances have to be VERY tight. If there is any loose play, a gear will slip and or chip/break. A good example of this is actually the older Arkanoid spinners. Almost all the used ones Ive seen are completely non-functional because of these very facts. Wear and vibration causing play... and then gears getting all jacked up. And an Arkanoid controller is fairly hard to jostle... vs... a Starwars yoke that gets Slammed around heavily and frequently.
Optical would be helpful with ultra high resolution encoders... IF... you could manage to have super precision in alignments, and IF you didnt have to worry about calibration. However, optical isnt good, because of the calibration issues.
And finally, you run into playability & comfort issues. The standard yokes handles are not actually that big... and fit the hands perfectly. If you make the handles too small, trying to control the thing will be very hard and awkward.
I think anything less than 3/4 traditional size is too small for good playability, with almost any controller type.