The paper, One More Bit is Enough, got me thinking. If the use of a SINGLE bit in the IP header can prove so dramatically useful, then those IP header bits must be very precious, all of them.
The volume of traffic on the internet is exploding. The amount of data we can store per dollar is exponentially increasing at a much faster rate than processing speed per dollar. The volume of data we store and transport just grows and grows. We seem to find ever more uses for data. Today, a gigabyte is no big deal. In 1988, I remember, there was still a huge 1 gig hard drive on the fourth floor of the Clyde building, about the size of two large refrigerators.
So today, when a gig is no big deal, why would it be too much to ask, to ask for three more bits, or 100 more? If we are effectively stuck with a fixed size IP header, in spite of IPv6, it seems that this is a very big problem and potentially a fruitful area for future research.