Reading about some of the missteps of CSP, much like the above, they seem to be share similar traits of government mishandling, bureaucracy, dodgy dealings, etc.
EDIT: In any case, a naive interpretation of the Pakistan project cited -- if it truly is getting ~20% of anticipated power, cost per unit is 5x forecast, at which point a CSP would have been better value for money.
I suspect that solar thermal is in more than a lull; I suspect that it's been obsoleted by PV and we aren't going to be seeing many new installations at all.
I also suspect that mirrors are less sensitive to dust than PV cells. And that it's cheaper to just install more mirrors (flat reflective surfaces) to compensate for anticipated dust build-up, than photovoltaic panels (per unit of area or per unit of power generated).
But, really, I expect there's a fair bit of research on this subject already out there.
As I intimated, it's probably not so much an obsolescence issue, as one of pushing the storage question aside. CSPs address generation, with some ephemeral (cloud, evening, etc) storage capabilities. As per the standard observation - it's going to be a blend of power generation and storage technologies that sees us through.
The storage issue is interesting, but doesn't matter so much to most plants since they tie into a larger balanced grid, and battery storage is coming down in cost at the same exponential rate as PV. These same advantages are not accruing to solar thermal. So I do think we are seeing the death knell for solar thermal, even when energy storage is desired alongside peak production.
Storage can't be ignored - and the 'balanced grid' that we're all part of relies heavily on burning fossil fuels for both baseload coping with peaks (sun goes behind a cloud or the horizon, or the wind stops for a while). As we decom more of the fossil fuel systems, a more robust & scalable storage system, even a relatively ephemeral one, will become more compelling. (my prediction : )