People will adjust and cope. Just as they always have.
Most won't like what that adjustment will look like if that scenario comes true.
How many of us have changed our habits? I know I walk, ride my bike, got a motorcycle that gets 60mpg, etc., and I CAN afford the increase (so far).
Walk? Ride a bike? I drive about 200 miles a week to work and back, not to mention my second half drives about 120 miles. And this is just to work.
Trust me, it goes anywhere near 5. per gallon, either everyone gets a big time raise, or things go belly up fast. Real fast.
I drive 200 miles a week - 20 miles each way. My wife drives 180 miles a day.
I own a diesel and am looking at a hybrid. I ride my bicycle to work two days a week and try to ride my motorcycle a couple more days.
The economy may go belly-up. But a lot of folks will adapt regardless.
I'm not saying it will be a good thing for the economy, just Americans a more resilient than some on these energy threads are willing to give credit for.