Look, when the price of oil gets high enough we will use something else.
Your question assumes static conditions and technology. Its like an 1870's American asking: What will be the price of whale oil in 1960 if 200 million American's want to light their homes. In 1830 if you found oil on your land it *lost* value. Land, after all, was for grazing animals and that filthy black goo ruined a perfectly good pasture. In 1920 if you found oil on your land, you were rich. What changed? Our Ideas. Thats it. We decided burning kerosene was easier than hunting whales. Eventually we even found a use for that pesky flammable waste product, gasoline
We can have as much energy as we want. The primary obstacles, as always, are more political than technical.
There is enough energy in the monitor sitting in front of you to run your state for the rest of the year. You just have to ask Nature politely to give it to you. We are not materials limited we are idea limited critters. This is the entire *point* of human beings.
This may be so but... this won't happen either. The only reason we, as a species, continue the way we are, is because the ability to produce huge amounts of energy is tightly controlled by a limited number of governments. When the genie is completely out of the bottle, then subsequent wars or terrorist activities are likely to reduce the world population to a fraction of what we have now.
A new beginning MAY be possible when the population drops to... maybe a lot less than 1% of what we have today.