I personally don't see why we don't start embracing nuclear power, at least on a small scale as "fill in" reactors. Yes, coal is old and dated but solar is only ever any good during peak daylight hours, it's very inefficient.
A nuclear plant will never pay for itself if used only for standby/peaking; it's simply too expensive to build them (and eventually decommission and process the resulting waste). If you want to have any hope of breaking even on a new nuclear plant you have to plan on running it at full capacity basically for every minute of its lifecycle. For reference, there's a PWR plant under construction in Florida was supposed to cost $5 billion and open in 2016. It's now expected to cost $22 billion and take at least another decade before it's completed (if ever). That puts the capital cost at close to $10,000/kW, which is much higher than DOE estimates for any other technology. At this point, nuclear plants are far too financially risky on their own merits for any sane private investor, so they don't get built without public financial backing, and all of the headaches that arranging that entails. I'm not even sure that the US government is willing to back them anymore.
Nuclear advocates will often claim that new reactor designs are better/faster/cheaper/safer, but it's going to be extremely difficult to convince investors and utilities that they're actually worth building in the current energy economy.
If you want to bridge the gap from now to full renewables, my understanding is that combined cycle natural gas is pretty much the best option (at least in the US). They're relatively inexpensive to build and operate, relatively efficient and clean to run, and well suited to variable loads which makes them good fill-in for solar/wind in the absence of adequate energy storage.
One nice thing about solar is that its output tends to correlate with some of the most problematic loads...air conditioners. After all, if you're running your aircon extra hard because it's hot because it's summer and the sun is beating down on your house...