Anyway, what does prepping for unlimited energy look like? I guess, favoring electrical over fossil fuels. But for normal people and the vast majority of companies, that looks like preparing for mass renewable electricity anyway, which is already a good thing to do.

With limitless energy you can have "fossil fuel" synthesized from air and water [1] and use existing "fossil fuel" infrastructure.

[1] https://www.wired.com/2012/10/fuel-from-air/

could also be just massively scaling up energy consumption with little concern for efficiency (since limitless would imply very low cost), which would probably be a bad idea for renewables, and in case of not-so-cheap energy also very expensive