Is what really matters to global oil prices peak oil? We may be on the brink of this now globally (it has been reached by many individual producers long ago), but it may be in the near to decade or two future depending upon who you talk to if we haven't reached it.
Or, is what really matters per capita peak oil? This arguably happened around 1980, and is only going to reverse if the global population starts growing more slowly than oil output, raising the bar for the oil industry to keep up.
I suspect that the number of people who live in industrialized economies or post-industrial economies is what really matters. Population growth in these economies is generically lower than global population growth rates, but it is growing because this is a function not just of natural increase, but also of economic development which is in two steps forward and one step back fashion gradually spreading to larger and larger parts of the economy. Since economic development is harder to predict than population growth, the trendline is harder to predict. Still, both population growth in the existing industrial and post-industrial world as a whole is probably positive for the foreseeable future and economic development is also likely to be more than zero, so oil prices are likely to have more demand pressure in the future as well as more supply pressure in the future. Hence, the measure of oil demand relative to supply that matters to global oil prices is likely to hit before peak oil does (if it hasn't hit already) and still sets a higher bar for oil produces to meet in terms of new production to keep oil prices moderated.
Equally important to this dynamic, of course, is that cheap oil may make economic development easier and cause the number of nations or subnational areas that are industrialized to grow more rapidly. But, peak oil driven price increases for oil may slow the industrialization phase of economic development. Thus, projecting future oil prices as a result of predictable supply and demand factors has self-interacting components.
The biggest wildcard is breakthough technology. New oil exploration and extraction technology could provide downward price bumps. But, the real game changing issue is whether technologies with a big impact on oil consumption take hold.
In practical terms this means mass conversion from gasoline and diesel powered vehicles to alternative fuel vehicles like electric cars, or dramatic increases in fuel efficiency from developments like plug-in hybrid vehicles and increased public transportation usage (particularly involving bus usage). Electric and plug-in hybrid vehicles of one sort or another are probably the only way that global oil demand can drop enough to counteract the long term price pressures that oil faces from an increasingly large industrialized world population and stagnating long term oil production as economically extractable supplies are exhausted. Transportation is the dominant source of oil demand in the industrialized world that otherwise gets its energy from other sources as environmental and price factors have made oil based fuels less attractive for uses where alternative energy sources are technologically viable. So these technologies have the dominant impact on oil demand per person in the industrialized world.