I'm struggling to see the point. Unless you've got a heavy sport clutch there is almost no fatigue (well unless you spend an hour straight in traffic) and the difficulty you speak of seems to only occur for the first few months of driving. On top of that, any fatigue there was is now moved to your arm instead and my legs have much greater endurance than my arms.

Regarding maintenance: assuming that the components are on the shafts of the gearbox then maintenance requires gearbox disassembly. Sure you could design gearboxes to have a removable access panel and removable gear assemblies but this would probably compromise strength and torque capabilities, and lead to packaging issues for the car makers. Replacing a clutch in a modern car is only not parts-expensive only labor-expensive and that is only due to the time required to access the gearbox/bellhousing. This will be the same if this product is used unless you convince car manufacturers to rethink packaging.

Regarding driving pleasure: The fun of the H-pattern is the skill involved (a sense of pride and accomplishment) and the high precision and speed of clutch engagements and disengagements (clutch kicking, clutch dumping, riding a clutch round a corner to keep revs up (ie early vtec car with unsuitable ratios for the track etc)). With your system you've forced the driver to take their hands off the wheel for some advanced techniques and reduced the sense of accomplishment. Given the coupling of input surfaces (ie clutch pedal and shifter are now the same thing) it may reduce the the options available to the driver. For driving pleasure I see almost no gain over a automated dual-clutch system (ie DSG etc) as the pleasure does not come from physically moving a lever but the aforementioned reasons.

Torque capabilities and upgrading: If you keep the same normal force (the pressing force between clutch surfaces in this context) changing the diameter of a clutch changes the amount of torque it can transfer. To have the same torque capabilities using your system in an existing car you will have to vastly increase the force applied to the friction materials as space restrictions inside the gearbox restrict your ability to use multi-layer or increased diameter clutches. Given the leverage available to hydraulic systems in current vehicles, the much larger friction surface available, and the larger diameter you're going to have a lot of trouble producing the same force while maintaining driver comfort. If you've already solved that issue (congratulations, wanna tell me how? :P) we still have the issue of upgrading the car. People who still love a H-pattern manual are the group most likely to modify their vehicles and the space restrictions of the inside of the gearbox mean multiplate clutch assemblies and high-torque clutches are gonna be either difficult or impossible.

I might be wrong though :)