Seeing the D somehow again in the show would be insane. A great way to say goodbye, with the crew back on the bridge one last time.
The nostalgia overload would be overwhelming!!!
I know already I'll be in bits watching the last episode.
I was thinking about this last night.
The only way to stop the integrated fleet will be bringing one or more of those older ships out for one last ride. Could end up being a way to Phantom Menace it and destroy the station or satellite that keeps everything integrated. But I am betting the whole TNG crew winds up on the bridge one more time, and then the TNG theme blasts full on as the camera pans over it leading the attack to save Starfleet.