If no one saw the most recent entry, Amazon has 7 "25th Anniversary of Knightfall" trades coming this summer and fall. 3 cover the first Knightfall Omni, 3 cover the second (Knightquest), and the last is Knightsend:
https://smile.amazon.com/Batman-Knig...ghtsend+batman
https://smile.amazon.com/Batman-Knig..._&dpSrc=detail
https://smile.amazon.com/Batman-Prel...G3MWDW7Q5GY0ZN
One might guess that the reason the second Knightfall Omnibus was split up w/the Crusade first and then the Search (instead of interweaving the stories chronologically) was for the ease of parceling the story out in to trade.
For those keeping track, that just leaves Prodigal, Troika, Nightwing: The Search for Alfred, and Vengeance of Bane II from the third Knightfall omnibus (so far) uncollected for the new 25th Anniversary Edition volumes. I wonder if the new Knightfall volumes will do something with their spines like the re-release of the Death of Superman (where the five volumes formed the bleeding Superman logo).