Renewables haven't scaled yet, even if they are making progress.
Nuclear is interesting in that we have around 70-90 thousands years of fuel for the plants, which can only get cheaper/safer over time as the technology gets better. Currently, their capital requirements (they are expensive to build even if they are cheap to fuel) and waste problems make them fairly unviable. Couple that with being even less on demand than coal...
Oh come now. 70,000-90,000 years? If the Nuclear Energy Agency (NEA) has accurately estimated the planet's economically accessible uranium resources, reactors could run more than 200 years at current rates of consumption.
Here are some example studies of where things could go: http://blog.ucsusa.org/mike-jacobs/suddenly-the-future-is-cl...