IF....
And I do mean a big if what the OP says was true.
I, and most of the membership will be retired/dead.
43 years is a long time.
Not to mention that there are plenty of sources of cheap fuels that are not "Fossil fuels". And fossil fuels is a misnomer. Oil isn't created by organic material decomposed under heat and pressure. It's a natural product of pressure and heat of elements already in the ground...and more is being produced by just abandoning a well and then returning to it some years later... allowing the geological process to produce sufficient quantities that make pumping it out effective again.
In the meantime...
Hydro-electric dams, goethermic (hot springs) , solar (not so good) , turning yellow coal into diesel, and other things of this nature (including nuclear power) are more than sufficient for power and transportation of goods.
The problem isn't energy...it's cheap and abundant energy.
And this energy is what is used to pump water and provide sanitation for our largest cities...as well as import food.
No water, sanitation, or food and large cities evaporate overnight.
And then everyone wants to move to the rural areas. (As if this works)
Chaos and infighting will destroy us loooong before we ever run out of energy.