Currently the price gap between 100LL and 87 unleaded, on a national
average basis, is approximately $1.50, give and take. That's quite a
bit higher than say 1997, I remember the gap was definitely below $1.

The total consumption of 100LL will continue to drop in the years to
come, caused by high end operators moving to turbine, and low end
operators reducing their hours due to escalating fuel prices. Logic
says that the price gap of 100LL and 87 unleaded will increase further,
because the special handling and transportation cost of 100LL fuel will
have to be amortized over a smaller amount of total 100LL sale.

I guess all the low compression engine flyers better get their autogas
STC and start lobbying their legislators for a stable supply of ethanol
free autofuel now.

Interesting sources:
http://www.airnav.com/fuel/report.html
http://www.fuelgaugereport.com/
http://www.fuelgaugereport.com/