Oil is going to get expensive; there's no particular guarantee that energy is going to get expensive, though. (It will if we mindlessly continue our current policies, but expensive energy will have a way of clearing our minds about certain priorities.) And given that we're talking decadal time scales, how will "sprawl" be affected when we're using time-shared automatic-driving electric cars (and generalized transport network)?

I think there's a lot of fervent hope from a lot of people that sprawl is doomed by expensive energy, but personally I rather expect that technology will end up "saving" it in the end, a further testament to the trend towards decentralization, not erasing it.