Yo, DD - I wouldn't necessarily call CF a profit driver so much as a profit "protector"; not only from the supply security standpoint, but also from the standpoint that every little bit of acrylonitrile volume lowers that unit cost, so there is benefit to Building Blocks as well. Also, the issue of energy efficiency is going to be much more critical than it has been in the past, but with dual drivers 1) the basic cost of energy and the increased demand for it and 2) global warming has just begun to weigh in here. The result will be that the choice of materials used in anything that moves as a result of energy input will be heavily impacted by strength to weight ratio ("CF" reporting for duty!) Bottom line: History, IMO, has little bearing here and any cycling to the down side will result from replacing carbon fiber with something better - but not before volumes have gone way, way up.
PS I'm sure Mr. Lilly & Co are hard at work at that "something better" as we speak!