If the government could make its mind up and stop wasting time, the US could rapidly diminish and even eliminate its reliance on fossil fuels
I'm not sure about that, unless by "make its mind up" you mean the government makes a big intervention into the economics, rather than merely streamlining the regulatory process. The crash in natural-gas prices has really killed the fundamental economics of a lot of nuclear plants that were in the works. With the huge up-front capital costs of nuclear plant construction, you can't compete in a market where cheap-to-build natural-gas plants can be fed by gas that's selling wholesale for under $3/MMBtu, barely above the price of coal. I don't see that changing unless either fossil fuels get hit by a significant tax (e.g. a carbon tax), or nuclear gets much larger subsidies than the current ones (which are mostly just loan guarantees and liability limitation).
Even in politically supportive areas, a bunch of operators who had announced planned new units in the early and mid 2000s (in places like Texas and Florida), announced around 2010-2012 that projects were being put on hold due to the unfavorable market conditions.