If Elijah already came, the Day he introduced is not an unused ticket.
Malachi’s last page is not a modern biography assignment. It is a covenant warning attached to a messenger.
Matthew 11 and 17 treat John as Elijah. The disciples want a later Elijah; Jesus says the role landed.
John prepared a people. That people saw the Day in their generation. Looking for a second Elijah to restart Malachi empties Jesus’ sentence.
The messenger came. The Lord he announced is the One you walk with now.