You ask whether a lens can lose sharpness over time, but then go on to say:
Please note, I am not talking about general wear and tear, or dust inside the lenses, nor am I talking about fungus in the lens.
Which are exactly the reasons lenses lose sharpness over time. So the answer is no - once you exclude all the factors which causes lenses to lose sharpness over time, lenses don't lose sharpness over time!
Clearly fungus on the surfaces of elements will degrade performance. Dust will too, but to a lesser extent. The other major factor is wear, lens elements are ground to very precise specifications likewise the position and alignment of elements is very important. Any shift in the position of lens elements over time, as a result of wear in the mechanical portions of the lens body (zoom or focus mechanisms) or knocks which cause parts to become dislodged, will degrade image quality.
Aside from surface effects (scratches and the degradation of coatings) the glass elements themselves will not degrade except in some rare cases (such as lenses with thorium added to the glass which brown over time).
For validation of the idea that lenses don't inherently lose sharpness, look a Panavision. Panavision is a company that rent their own very high end lenses and cameras to the movie industry. Renting out their own gear means they take a slightly different approach to lens design.
Repair and replacement are both profit generating enterprises for most camera manufacturers, i.e. when you send you lens in for repair once it's out of warranty they will make a profit on the work done. Likewise when you replace your old lenses.
Any time Panavision spend repairing their lenses is pure loss as those lenses are not available for rental. Likewise replacing lenses only costs them money. As a result lenses are designed to be easily maintained, easy to disassemble and clean. Elements are not fixed in place but sit in adjustable mounts with grub screws that can be turned to correct tiny errors in positioning as the lens barrel wears.
As a result they have been renting out the same lenses for location shooting in extreme environments for decades, and they're still as sharp as the day they were first made.