If you decide to fly at a different level without telling anybody you could mess up that plan.
Sorry .. it was a dumb question
Now I have watched the CD it doesn't seem like much has changed beyond now having to ask for a "Basic Service" rather than FIS. Presumably not using the word "maintain" does not imply an agreement.
Overheard on Saturday
ATC: What is your estimate for X?
Aircraft: er...um.. er....
(Break in transmission. Long pause)
Aircraft: I don't know. I'll need some time to work it out.