I like when you said "replacing oil and gas is not as easy as some people think" oil and gas is still very important infact it's plays an important role in human existence since it's a mineral resource however instead of replacing it totally there would be alternatives for instance there's fiat and there's Bitcoin, Bitcoin won't completely replace fiat but would serve as an alternative, that's how it would be concerning oil and gas and other energy resources in the future. That's why not everyone is buying the idea of electric cars currently cause they still believe that petroleum powered vehicles are still very useful, maybe in the future their use case would be minimal but they won't be completely eliminated.
Think about it, it's no coincidence that superpowers like the US are trying to stockpile as much oil as possible, and they are one of the countries with the largest oil reserves in the world. Or all the wars in the world today are about fighting over mineral resources and oil is one of them. So to say that they will be replaced or eliminated anytime soon is just wild speculation.
Bitcoin will not replace gold or fiat currencies, and similarly, alternative energy sources will not be able to completely replace oil and gas.