Much of the falling costs are a result of dumping - which is selling at an unsustainable loss in order to capture market share and then jack the price up later. So assumptions about continuing price falls are unsound.

There is no decent prospect of mass energy storage any time soon, and likewise little prospect of moving electricity from the places where it is nice and sunny to the ones where it is cold and dark. So both of those links are worthless. Solar cannot replace other forms of generation, it therefore comes with the cost burden of maintaining an equal but idle infrastructure. It's a fairly simple calculation. On the one hand you have the billions it costs to provide X number of gigawats day and night with old fashioned things. On the other you have the cost of providing Xgw with solar power in the day and with the other stuff at night. Which is the same number of billions, plus the billions required for the solar infrastructure - which is going to be a bigger number. You can't even count on saving much fuel - it's incredibly inefficient to turn a power station off and then fire it up again at night.

It's doubtful there is such a thing as a price point that solar power could reach which would justify that expense - but it would have to be disposably cheap.

One option is using solar to generate fuel, rather than direct electricity. That might be done using bio-hydrogen production from a green alga, which is just one area being researched.

Well most elements are, but it's a question of getting them into the form we can use. Try making girders out of hematite . According to wikip, thorium is something like four times more abundant than Uranium and is easier to refine. But that's still not the same as hydrogen for fusion reactors, which is almost literally everywhere.

Fusion is undoubtedly the way we need to go but we're still apparently 30-40 years away from having a fusion power station online. Which we have been for about the last 30 years...

Yes but for fusion you need deuterium and tritium and that needs to be separated from the sea water.