hmm, i'll have to punch out a histogram stacked line graph over time of how imports are divided. it could get interesting then. if we show increasing heavy crude import and increasing light prices, then the US has effectively hedged against rising oil prices!

Exactly !

The US by upgrading its refineries to handle "junk" oil is optimizing itself for the long term case of ever increasing oil prices. This is probably the underlying reason that WTI has become decoupled from global oil prices in the US at least the need for light sweet crude has dropped dramatically.

I'd have to guess the same is happening in Europe and Asia.
It may well buy use several years of below 100bbl oil I don't know. But maximizing the abilities of the refineries to handle any oil and optimize for any product is probably whats keeping the current situation of zero production growth from causing price spikes over 100 now.

Overall the move to complex refining can only do so much before absolute supply begins to be a issue.