You can't see peak oil, really. You'll just observe more and more "unexplained" fluctuations in the oil price, oil reserves, and subsequently the global economy.
I suspect we'll go up and down for many years while it gradually becomes more and more expensive to drill oil all the time. The supply and demand fluctuate due to speculation, unsold reserves, and reactivity of demand of oil, so it will be hard to see the bottom line. It's not going to be cheaper than today in 20 years, and that will inevitable manifest in the global economy.
I suspect we'll go up and down for many years while it gradually becomes more and more expensive to drill oil all the time. The supply and demand fluctuate due to speculation, unsold reserves, and reactivity of demand of oil, so it will be hard to see the bottom line. It's not going to be cheaper than today in 20 years, and that will inevitable manifest in the global economy.