Eddie Hearn had confirmed Anthony Joshua could step aside and allow Oleksandr Uysk to fight Tyson Fury.
Joshua has been negotiating his rematch with Usyk and had been expected to announce an April date at either Wembley or the Tottenham Hotspur Stadium.
And Fury is due to face Dillian Whyte in a mandatory defence of his heavyweight belt with purse bids due on Friday.