Wait, isn't "peak oil" about running out of oil reserves? Or am I getting my hyperbolic predictions confused?
Most reserves have already hit or passed that point. Most oil today is more expensive than it was, say, in the 70s because you have to inject water to force it to the surface and things like that. Just digging a hole and watching it gush skyward from internal pressure is a thing of the past, basically.
There is also a finite amount of oil in the ground. It's stupendously useful and rich in chemistry. We still don't know where all the reserves are, and there is a lot of oil still in the ground. But that oil comes at a cost: inconvenient, excessively deep, politically untenable. But we'll be able to get oil for a long time (just at ever increasing costs).
Put another way, you can, for a crude estimate, divide national GDP by petroleum consumption to arrive at the net economic gain per barrel of oil consumed.
In the U.S., that's about $1,000. For India and China, it was about $400 - $500 as of a couple-three years ago. For much of Europe, about $1,500, peaking with Switzerland at about $3,000/bbl.
Put another way, figure what you spend to get a barrel of oil, and subtract that from what you gain by it. Or divide to get a multiplier. At $10/bbl cost and $1000/bbl value, the US gains $100 for each dollar spent on petroleum. At $100/bbl cost, that falls to $10 per dollar.
For countries with lower value per barrel, those gains are even smaller.
A couple of other perspectives:
* In India and China, there are low-value activities enabled by energy usage which would be driven out by higher energy costs.
* There is the question of total net energy. It's one thing to say "but we've got $10/bbl oil". But if there are only, say, 10 billion barrels/year of $10/bbl oil, vs. the 35 billion barrels consumed annually, well, that's 25 billion barrels/year you've either forgone or need to substitute by other means. And our substitutes for petroleum, most especially in transport, are exceedingly limited.
* There's substitutability, generally. Passenger vehicle traffic may be electrifiable. Transit and cargo freight as well. Marine freight not so much, and commercial air travel almost certainly not at all. Options for alternative liquid fuels are at best highly problematic. Some exacerbate current problems, most create new ones.
But answering your point: what's changed isn't the amount of fuel, or the benefit gained per use. Rather, market price has climbed (and fallen, and climbed, but that's another story, unless you owe or hold loans based on market price assumptions...) to the point that previously noneconomic reserves are now economically viable.
The limit of energetically viable deposits is, however, a hard cap, and barring some massive developments in technology, are unlikely. There's that little emissions problem as well.
Hydrofracking is a technology which was first developed in the 1940s and 1950s. It wasn't used until the past decade simply because it wasn't necessary or viable. And while there've been some select specific technological improvements in application, the fundamental concept is as it was first conceived.
The problem is that as the oil price goes up oil that was not economically viable in the past suddenly becomes viable and so peak oil will shift a little bit into the future.
Eventually it will run out though, it is a finite resource after all.
Peak oil is about the point where oil production (weird word for moving it from below ground to above ground, but part of it is refining) is largest.
We would be fortunate if that ends up being near the half way mark, as that would likely mean that production wouldn't fall abruptly.
Also: I hope we will never run out of oil. Ideally, alternative energy will get so cheap that it will become uneconomic to get out the last x%.