I agree it will be temporary. But I am guessing it will be driven more by increased demand in C1 rather than a saturation of Natural Gas Liquids. NGLs are not as expensive to transport and the world begs for cheap plastic. Consumption is easy to climb with developing countries. Also we can keep the NGLs and build more facilities to export polymers.
C1 for transportation is going to increase. There is too great a difference in $/BTU.
We are in absolute agreement on THAT point. The only questions at this point are by what path, and how fast. I tend to think mostly of road transport ($4.50 gas (which is what I paid yesterday) tend to encourage me to focus that way), but the train and ship connections are likely to come sooner, especially with the C1/diesel "hybrid" technology mentioned upthread.