I don't think AJ needs a new trainer again. He just should accept his Level of boxing and let the pressure go. He still can beat a lot of good guys in the heavyweight division. He should do now a decent step back fight and get some confidence again.
The trainer doesn't matter now. He has had the best training money can buy for a long time. They have always brought in special additional trainers and so forth to fine tune this and that. It's not like he was just out chopping wood with Uncle Peter then hitting tyres in the old shed complex. He will never get any better. He's peaked and it's actually all downhill from here. His physical prime is over and he's taken a bit of damage now too.
With Sugar Hill no longer with Fury, I think he could be useful, also Virgil Hunter. He needs a trainer who knows how to teach him to frame, collar tie and utilise his size and strength up close. He's needs to learn to manhandle smaller men like Lewis, Wlad and Fury did, it's a big hole in his game. He's never going to be fast enough to catch someone as quick as Usyk or slick as Fury if he doesn't learn how to force opponents into positions he can land with his punches. If you are not quick enough to get into positions to land then you need to stop your opponents in their tracks and push and pull them out of positions making them reset so they can't land themselves because they are not in a position to throw. It was frustrating watching AJ fight last night, it was clear very early on he hadn't learned the right lessons from the first fight and was unable to really take control and spent the fight once again fighting at Usyk's pace and distance.