I spoke extensively with Mark Jenks, VP of 787 Development during my visit - he was very confident that the short time frame for certification could be be achieved given that around 2/3's of certification has already been done without actually flying.
Personally, I would not be surprised to see delivery slip for one reason or another, but unlike previous setbacks on the 787, the entire ethos and grind towards first flight is different.
Even Airplane #2 is looking great, engines and major systems installed and a high level of work going on in the 787 line - the key thing is how quickly they get al 6 test airplanes flying. That will be the ultimate benchmark as to whether their achieve that Q1 2010 goal.