While the touchpad on the DS4 is under-used and imho pointless, i could see a smaller 'touch area' working as a means to add at least 4-5 additional buttons (via gestures ... swipe up, swipe down, ... as well as click) within a relatively small area on the controller.
I loved how many games already used the touchpad like that - each individual swipe gesture leading you straight into a specific menu, like up is map, down is inventory, etc.
Also, keep the share button but make it way more snappy within the OS.
Or just let us allow to bind a specific input (like click-and-hold, or double click) to "save screenshot / video clip and upload right away"
I always upload (as visible "only me") all my 15 minutes clips and do curation after the fact.
Like, the DS4 is pretty decent. Shrink the touchpad, enable us to turn off the LED altogether and maybe remove the horrible tiny speakers and we're getting somewhere.