Nacht's death is something that we have been speculating from the beginning of the Spade Kingdom Arc. His sudden appearance in Clover Kingdom and training Asta to control his Devil is an indication that Nacht already had a rough idea about his death. On top of it, Nacht is overpowered since he can control more than one Devil. And, in the latest Chapter he says to his Devil to get ready to die. Hence, there is a possibility that Nacht will ultimately die, and Asta will reach the battlefield after this disaster has settled down.