Who knows about the culprits behind high costs? I think we'll find out pretty soon with the next plant. If memory serves lawsuits drove the cost and unpredictability of nuke plants past the point of feasibility. We'll see if that's still the case.
The intervenors have learned to game the system to stretch out the completion time so much that the projects become economically nonviable. They know that you can kill any capital-intensive project if you delay it long enough, because the carrying charges for construction-in-progress-but-never-operated eventually reach the point where you have no (or negative) return on investment. Then you go bankrupt and the project is either killed or taken over. That was the wacko gambit for Diablo Canyon (completed for ten years but not operated) and Seabrook.
And that goes for any capital-instensive project, not just a nuclear plant. It could be an oil refinery, or an airport, or a transmission line, or even a windmill farm like Cape Wind (and a nod to you, Kennedy scum, Teddy and Robert Jr.).