Got my answer from Apple. They will not credit back existing subscriptions when you sign up for Apple One. I will just wait until they expire and look at Apple One again.
@jidabug it won’t Realy make sense for us until the prepaid year of Arcade is through. Grandsons use it all the time.
@hawaiiboy That makes sense. We haven’t paid for Arcade yet, so between the music and iCloud subscriptions, we’d come out ahead and Arcade would basically be a bonus. 😄