(given the current prices and technology).
Things have been changing so much that we will always have new technology to get oil. The last barrel may cost $1B but capitalism will provide it if they can find a buyer. New fuels and things will change faster than we can imagine.
Then we won’t get that last barrel.
When oranges start costing too much,
we switch to something else.
Basic Economics: A Citizen’s Guide to the Economy; Sowell