“Peace be with you” isn’t just used at confirmation. It’s used by all bishops, always, instead of, “The Lord be with you,” as is used by priests and occasionally deacons. “Peace be with you” is one thing that is not changing this Advent.
Now, we all know that the Missale Romanum translation is changing at the start of Advent. Contained within that edition, bishops still say, “Peace be with you,” as they say right now with our current translation. In the new translation, the response to the bishops’, “Peace be with you,” is our, “And with your spirit,” which is also rendered to the priests’, “The Lord be with you.” Therefore, logically, this, “And with your spirit,” because it will be used at mass very soon, it should also be used during confirmations.
I hope this makes sense.