AJ has to get past Usyk first and even then it's if (a very big if) he beats Whyte, which I don't think he would.
Even if Joshua lost to Usyk again, Fury Vs Joshua is a HUGE fight. Both men will 100% fight eachother at some point.
If he quits now, I don't see him cracking the top 15 ATG list. All he did was beat old man Wlad and an admittedly courageous and powerful Wilder. He needs to beat a Joshua, Usyk, or Ruiz or live under even an underachiever like Bowe. Even Norton had two Ali wins and what was considered a win by many people over prime Holmes. Nothing Fury has done approaches that.
Tyson Fury is mentally much like a child that is desperate for attention. I watch his fights but that's it, I think the man is a bit of a moron but a very good boxer.