I sent my 1996 Seamster 120m off the be serviced recently, along with some other things done, new dial and bracelet. I was informed that Omega likes to restore the watch to original condition, as the dial had been changed to blue, and so they would probably want to change it back to white. I told them if they have blue then I would prefer a blue dial but if not white is fine. Upon inspection of the watch arriving at the service center, I was told it needed a new bracelet, as my old one is worn beyond polishing. Since the watch is 20 years old, do you think Omega will just replace the bracelet with the closest one they can find, or will it be NOS parts? I can't wait to get the watch back, and see what it looks like, as well as be able to wear it again. Thanks everyone for your answers.
When I sent in my wife's old aqua terra they said that they would simply replace the movement. That piece was a modern piece though so I'm not sure what they would do for a vintage movement. Like @Mouse_at_Large said, all we can do is speculate.