If solar really does drop in price significantly and has a big impact, wouldn't that lessen demand for coal/natgas/etc? A drop in demand will lead to a drop in the price of those fuels everything else held equal.

Of course, maybe the declining supplies of fossil fuels will cause fossil fuel prices to rise. But what about advances that make the extraction and consumption of fossil fuels more efficient?

I'm just throwing these things out there because there's a lot of economic dynamics that could move targets like "grid parity" significantly.