Looking at the last 100 years and projecting forward I can 'predict' an economy changing back from its present 2% of workforce employed in agriculture back to some 20% by 2060.
The exact timescale is in question. The steepness of the downslope of the Hubbert curve depends on demand for oil and its products. If these stay high we can expect a steep downslope which compresses the timescale. If demand reduces the rewind takes longer. Of course, if you are in the oil business the goal is to maximise profits which is best done by ensuring that demand exceeds supply as much as possible, as it has done in the oil crises of the last century.
The story is set in 2060. Describing a society that is an exact mirror of the past period is not interesting. We would, I reckon, be able to maintain some of our technology. A society with computers, the internet and television but without mass, cheap travel.
There is still oil, but it is very expensive. There is some combustion powered aviation, for the super rich. You can buy a small electric car as good as a 2010 combustion powered car but, if you are member of the 20% of the agricultural workforce you can't afford one. You either walk to work, or if you are lucky, go by bike. But you do consider yourself lucky because you are employed and with the healthcare benefits of an employed citizen.
Working people cannot afford to travel much. They see the past century, the Time of Plenty, which is accesible via TV and films, as a lost golden age of apparently universal wealth.
The middle class are much reduced as a percentage of the workforce, many formerly middle class professions are automated or have disappeared as a consequence of the increased cost of hydrocarbons. But the lifestyle of the middle class is superior to the present day.
The upper class, the super rich, are almost invisible to the naked eye. They travel the world in combustion powered aircraft. They have ownership of wilderness areas and have longer, fulfilled, healthy lives. Just occasionally they come down to earth to influence the world of men.
In some countries there is a virtually abandoned underclass with no rights, no healthcare and almost no social mobility. Such is my model of 2060.