Was thinking in the same timeframe.

long enough for mechanisms like rationing and biofuels to eke out supplies along with crash programmes to move away from petro-chemical based argiculture.

That again sounds more like could than would (with the exception of biofuels, for which afew et al calculated a very low potential). If the process takes five to ten years, I'd 'count' on leaders to abandon any idea of a crash programme at the first sign of a recession, and keep to it for too long.

_{*Lunatic*, n.
One whose delusions are out of fashion.}