[badpun]

Energy problems is just one of ways in which our societies can get into a decline. There's also loss of arable land (industrial farming is slowly but surely destroying the soil across the world), destruction of biodiversification, leading to freak incidents (one pest/disease wiping out lots of crops, forests, farm animals, or humans for that matter), depletion of minerals in the Earth (who knows if even right now there's even enough lithium available for widespread deployment of electric cars etc.

[tuatoru]

It's technically possible now to synthesise carbohydrates, fats, and proteins directly from the air: in effect, doing artificial photosynthesis at something like 200 times the efficiency of natural photosynthesis, without using land.

With cheap enough energy and more practice (descending the engineering learning curve) producing food this way may be profitable in 30 or 40 years. We can re-wild all arable land.

There are at least dozens and possibly hundreds of alternatives to lithium chemistry for batteries, that are nearly competitive with it. Some of them are better than lithium in some applications. Watch for CATL's sodium batteries.

But say it's worst case, none of the alternatives turn out to be better cheaper, and more environmentally benign: no problem. There most definitely is enough mineable lithium. There's a temporary shortage of lithium refining factories.

If we had to, we could get by with water, rock, iron, sodium, potassium, calcium, phosphates, carbon, aluminum, and trace amounts of other things. The minerals we need a lot of, we have a lot of.