Joshua and Fury were locked in for an all-British showdown for the undisputed heavyweight championship in Saudi Arabia last August but the latter was ordered by an arbitration judge to face Deontay Wilder for a third time instead.
But Hearn is adamant they will eventually get it on as soon as possible.
Speaking to DAZN, he said: “I think the AJ Fury fight is still the fight.
“I had a guy come up to me today and ask ‘when’s AJ fighting Fury?’
“I’m kind of like ‘well that ship’s sailed a little bit, we’ve got a few things to work out still, and AJ is rematching Usyk’.
“And the guy says ‘oh is he? Well when’s the Fury fight then?'”
“That’s the fight that people still want to see and will always be there. The bigger the better.
“That fight, I promise you, will happen, whether that’s late this year or early next year, Fury vs. AJ is a dead cert to happen because it’s too big a fight not to.”
Joshua was left disappointed after the collapse of the Fury fight but insisted that he will do everything in his power to ensure they will finally meet in the ring.
But Fury says he can’t see it ever happening as he slammed the former two-time world champion for losing to Usyk in the first place, calling him a ‘big useless dosser‘.
The 33-year-old raged: “I cannot believe that AJ has gone and given Ukraine all the heavyweight belts back, after all my hard work of getting them.
“You big useless dosser! You’ve let a little steroid man come up from middleweight and set about you and take all your belts.
“It is going to have to take a real British Lancaster Bomber, like me, to go and relieve the useless little steroid head of the belts and get them back to Britain.
“You useless dossers! Bring them to me, the Gypsy King. Bring them to me and I will put them in their place and relieve them of the belts again.”