Humanity lucked out that solar and wind costs were driven down as rapidly as they were through manufacturing scale. We'd be screwed otherwise ("ie business as usual carbon output estimates").
Somewhat related but unrelated: it's not bad if fracking goes south. It'll drive the price of natural gas up, which will make existing nuclear and existing/new renewables more cost competitive. It'll also drive adoption of energy storage faster. We want natural gas prices to rise, since we're not going to internalize the CO2 emission cost through regulation. This allows for market forces to kick in that are beneficial to climate change mitigation.
Disclaimer: I have brokered one tax equity partnership arrangement for a solar plant rated @ >1MW (Indianapolis suburbs), and have done my research.