There's still a metric buttload of SONET interfaces in the core that won't go above 4470.
So, you might conceivably get 4k MTU at some point in the future, but it's really, *really* unlikely you'll get to 9k MTU any time in the next decade.
Matt
Agreed. But even 4470 is better than 1500. 1500 was fine for 10G ethernet, it is actually pretty silly for GigE and better. This survey that Dykstra did back in 1999 points out exactly what you mentioned: http://sd.wareonearth.com/~phil/jumbo.html And that was over a decade ago. There is no reason, in my opinion, for the various peering points to be a 1500 byte bottleneck in a path that might otherwise be larger. Increasing that from 1500 to even 3000 or 4500 gives a measurable performance boost over high latency connections such as from Europe to APAC or Western US. This is not to mention a reduction in the number of ACK packets flying back and forth across the Internet and a general reduction in the number of packets that must be processed for a given transaction.