Boeing has NOT raised their estimates of the market, which is why they haven't launched an all new aircraft.
In 2004 Boeing estimated a marked for 500 very large aircraft over the next 20 years. This year they are saying 1000. I would call that a raise.
In two years Boeing have doubled their estimate. I would say they are aligning themselves with the estimates made by Airbus pretty well.
And, as I said, it seems that the potential 748i customers Boeing have spoken to, want a bigger aircraft. Even at the expense of range.