I focused on wind because it's the weaker of the two. Solar has some promise, if the price of the cells comes down (or their efficiency goes up). If you could get a relatively affordable and efficient solar material that could be used for distributed generation (e.g., on everyone's rooftops), it could be a major contributor to the solution. However, with current technology, I still don't think it's anywhere near as promising as nuclear.

I'd be interested to see the math. Based on current small-scale panel technology's cost, how much would it cost to replace fossil fuels? I haven't crunched the numbers, but my guess would be that small-scale with cost more per mW than large scale (based on basic economic principles), and already large-scale solar isn't terribly economically competitive versus nuclear, much less versus fossil fuels.