The Lord's prayer, spoken in the first century by Jesus, is an acknowledgement that God's will had already been completed in heaven.
That is your interpretation and conclusion. I disagree that God's will was being done in heaven in an absolute sense before Satan is kicked out and that event had not occured when Jesus uttered those words. Compare Rev 1:1 (soon) with Rev 12:7,8. It was not God's will (for one thing) for Satan to reside in heaven, (his activities there, converting angels to demons, etc.and as my previous post explains) and that is why God had him kicked out. In a relative sense, God's will was being done on earth when Jesus prayed to God for the cup to pass him but it did not as it was also being done in heaven when God manipulated events so that Jesus could come to earth and save mankind. God's will is being done in heaven in an absolute sense when God becomes king and that happens after Jesus died loyal, is resurrected, exalted, becomes the Messianic king in heaven and that had not happened when Jesus said the Lords prayer. The basis of ousting Satan if you take the time to read the book of Revelation is the blood of the lamb and there was no basis when Jesus said the Lords prayer because the Lamb had not died faithful to God yet. READ REv 12:10
Anyway, that is what it seems to me. Just my opinion.