So basically it's very likely to be Dillian Whyte at Wembley in April next year.
Then the winner of Fury v Pulev later in the year.
It's looking like we won't see AJ face Wilder or Fury until 2020.

“The WBO is next [mandatory for Joshua], so it’s all down to what the WBO decide,” Hearn told Sky Sports. “They are going to review it at their convention, which is right at the end of October.

“Dillian Whyte is probably the frontrunner right now for the WBO mandatory, and then after that it’s IBF mandatory, which is the winner of Hughie Fury against Pulev. That’s probably not going to come round until the end of 2019.”

https://www.badlefthook.com/2018/10/...anthony-joshua