It's all about the balance between the cost to produce and speed of consumption.
As more extreme measures are needed to access fossil fuels vs. green energy becoming produced ever more efficiently and in different ways.
Fossil fuels will dwindle, wind, light, water won't - at least they will if we control global warming.
We will also continue to use energy more efficiently so that also offsets any increase in costs and also find cleaner ways to produce, store and dispose of things like batteries and solar panels. Plus, as more of us use renewable energy, the cost to manufacture the components drop.
In any case, we need to stop consuming fossil fuels becasue we also don't know what influence we are having on the internals of the planet, let alone the more obvious ones from global warming.