If he beat Usyk and fury then I'd argue he would be an ATG. If guys with resumes like Liston and Tysons can be considered ATGs then I dont think AJ would need to beat Fury, Usyk, Wilder, Joyce, Whyte again, and Hunter, all with devastating ease and then dominate as champion for 10 years, just to enter the discussion.
Tbf if he beats Usyk and the winner of Fury/Wilder he's there for me. An ATG who's vulnerable in the chin department, but cleared out a very solid HW division.