The realistic view: There is a very long way to go before renewables take over, and very little time
Many people assume that once wind and solar become cheaper than coal, oil or gas, the whole world will rapidly switch to them. But in a free market, wind and solar energy could get too cheap to be profitable, because too much electricity will be produced whenever the sun shines or the wind blows. That means companies would stop building new wind or solar farms unless there were cost effective ways of storing the energy from them.
And if demand for fossil fuels starts to fall, they may get cheaper as producers try to sell as much as they can while they are still able to. This may already be happening with coal, and some countries are taking advantage by burning more.