I would also add computational complexity. We're increasingly willing to throw more transistors at video decoding and encoding due to their reduced cost and increased performance, so the algorithms can become more complicated, have larger perform larger searches, etc. If you think about it from a power perspective, the power cost of a bit of data transmitted to a mobile device is pretty large. I would expect to see video compression formats increase in complexity until the power cost of compressing away one more bit approaches the cost of transmitting one more bit over the network.