Rutherford has given his word that he wont walk for nothing. A lot can transpire in the league from now until the 2023 TDL.
Players get injured, teams underachieve, and GM's are under pressure to right the ship.
Personally, I'd rather see Miller walk, than get fleeced trading for a middling 3C, a 3rd pairing D man , and a 26th OA.