There are also pipeline benefits of solar R&D and innovation.
- Replacing silver with copper,
- Harvesting more of the spectrum - especially if we can tap UV for cloudy days.
- Capturing/using heat - PVT.
Even if the cost of the solar panel itself doesn't drop, if that panel captures more energy, or lasts longer, that lowers the LCOE.
I don't think we are close to the point where the law of physics determine what can be done with solar, the laws of physics say there is a complete light spectrum to play with.
Then consider lowering the cost of embodied energy, better mining and processing of raw materials, streamlined installation etc.
It is more likely to be a marathon that a sprint, but we may only be halfway through the race.