The roadblock is the immense expense of a massive, complicated, intricate machine requiring massive workforces of highly skilled construction labor.

Shifting from heat conversion to some sort of direct conversion, and in the process ideally eliminating a huge amount of the construction expense, is the way out.

As our economies become ever more advanced, skilled labor becomes ever more expensive. Our existing fleet of nuclear reactors is much like the intricate cathedrals of past centuries. We could build in that style, but the expense is much higher today than it was back when the cathedrals were first made.