The difference is that the world economy did not run on whalebone. A whalebone price spkie did not tank the global economy. There was money available from a functioning economy to pay these progressively higher price spikes. Each time oil hits >$90/b the economy tanks, so can real oil prices keep repeating the above pattern for long before a market of $'s for oil ceases to exist?

Microhydro:

probably all the way down to EROEI <1. (It might be economical to pump oil for chemical feed stocks)

Is is credible that there will still be a chemical industry pumping anything if(when) we are down to oil EROEI<1? Pumps powered by what exactly? (I don't presume the answer is no, but I wouldn't rule it out.)

Pumps powered by wind would do nicely.  There are plenty of pumpjacks in Texas up through Kansas with plenty of wind, and excess might even be fed to the grid.