I absolutely loved this scene where Blair posed before the cameras after Serena gained publicity from being arrested :)
Like the title, it is time to say Goodbye to our most loved series. Okay I'm kidding, most of our series are meeting their finale stage and don't seem to be coming back. Gossip Girl is not falling into this category as it was picked up for another season.
Confirmed by Gossip Girl Insider
In fact Gossip Girl did say Goodbye ...to high school.
'The Goodbye Gossip Girl' marked the end of high school and the beginning of college, for Gossip Girl as well. Which could also mean that Gossip Girl is a part of the Serena, Blair, Dan...etc year group.
As for College:
Serena is off to Brown
and Chuck, well he's all going to be all independent and take over his father's business.