Joshua, the unified heavyweight world champion, will next fight at Wembley Stadium on April 13.
His opponent, yet to be named, and it could hinge on Saturday’s fight between Dillian Whyte and Dereck Chisora.
Whyte previously fought Joshua when the latter was British heavyweight champion in 2015.
Joshua won via knockout, brutally stopping his rival in the seventh round.
Since then, he has gone on to become world champion, unifying the belts twice.
Whyte, however, has teetered on the verge of fighting for a world title, but has not had the chance to battle for world honours.
And Hearn believes the pair could collide again on April 13, if Whyte wins this Saturday.
Speaking to iFL TV, he insisted that all options are still on the table for Joshua.
“Everything is up for negotiation,” Hearn admitted.
“We want to box on April 13.
“Believe it or not, AJ is passionate about British boxing.
“He wants to bring that fight over here.
“If there’s no way for us to do that fight other than by going there, that’s a decision he has to make.
“Not me, I don’t make the decisions regardless of what people think.
“Anything could happen, they could do a rematch [Fury-Wilder] which would mean we have to wait.
“Everything is in the air.
“Don’t be surprised if we fight Wilder at Wembley, don’t be surprised if we fight Fury at Wembley, don’t be surprised if we fight Whyte or Chisora at Wembley, don’t be surprised if we fight Miller at MSG, don’t be surprised if we fight Wilder at MSG.
“I don’t know how what will happen.”
EDDIE HEARN’S FOUR OPPONENTS FOR JOSHUA IN 2019
Anthony Joshua vs Deontay Wilder
Anthony Joshua vs Tyson Fury
Anthony Joshua vs Dillian Whyte
Anthony Joshua vs Jarrell Miller