As coking becomes more common expect significant price increases in asphalt and heavy oils.

It's already starting to happen. I knew that asphalt prices have been increasing, but I ran across a graph while I was working on this article that shows that prices have really skyrocketed. You can see a graph of the increase here:

http://www.techtransfer.berkeley.edu/newsletter/05-4/highprice.php

Now, the bulk of that rise goes along with the price of oil, but as oil prices go higher refiners will feed more asphalt to cokers when they can, causing an asphalt shortfall. This trend will get worse going forward, but at some point asphalt prices may be high enough to cause some refiners to reconsider installing that coker they have been thinking about. But we have a ways to go before that happens. Economics still strongly favor installing heavy oil processing facilities.