I doubt that anyone would believe it if these claims were made.
By the time an upside limit in capacity is accepted as a truth, the thing would go silly with people not only speculating but stockpiling.
I'd personally count on the Yanks buying up as much oil as possible so they can hold all the trump cards should a genuine depletion be apparent. All about power! Long term, I think you'd see lazy fat cat fcukers finally making an attempt to be more efficient- something long overdue for a lot of heavy oil users.
As a sidenote, it would be interesting to see what alternative means of fuel/vehicles/machinery would crop up as a result.
Surely, surely, surely, what with advances in solar power, hydro-electrics and glucose as power sources, some very rich people are paying some very bright people to shut the fcuk up about their alternative power sources etc.....