[cbush]

There will always be gasoline- at a price. But even if gas was $10 per gallon, many of us don't put that many miles on our Porsche where it would make a big difference. We would probably chose another car for a daily driver.
I think early/mid 60's British sports cars are a good parallel. They are really only useful as hobby cars- much like the Porsche 356s of their era. The rare ones hold their value or appreciate. Others don't. The point being, as (or if) we get away from combustion engine cars for every day driving, then our cars become hobby cars. The interesting ones will be valued accordingly. But in context of all the cars out there, what cars made in the 70s/80s hold any real interest to collectors? We are probably better off than enthusiasts of most other relatively high volume brands. I would bet my money on an 85 911 over an 85 Mustang GT.