My fundamental hope for humanity is that someday, rather than having to confront social challenges around distribution of resources (who gets more water? who gets more land? who gets more oil? do we need to raise energy costs to capture the extrinsic costs of polluting the air?), we will just have enough and more of everything.

The Central Arizona Project and the Navajo Generating Station are my favorite examples of this. The Navajo Generating Station is a giant coal-fired power plant, which provides energy used primarily to pump water up into Arizona. The station substantially degrades air quality in the surrounding areas, and the water that is "stolen" from the Colorado is a part of the West's growing water concerns. Right now, there are two sides to the issue: those who think it is worth the cost to bring water to Arizona, and those who believe the environmental issues are too big. We could solve that like a social problem, using politics and ethics to try to make the decision... or we could just get on making energy cheap and clean, and suddenly a huge part of the cost disappears. If there was no fly ash issue, no NOx issue, no CO2 issue, then we're back to just worrying about the water flow. But if we have cheap energy, desalination suddenly looks a lot more palatable, which would reduce a lot of water pressures in the US. Los Angeles could switch to 100% desal water and the Colorado river would have a surplus of water again.

Cheap (and preferably clean) energy, solving climate change, and cheap access to space (this one is more dubious) would all broadly boost the quality of life for humanity.