He just needs to beat everyone left there is to beat. I don't see that "defining" ATG or rival coming along. He will be great kinda like the same way Chavez was great or KT is a great. Beat alot of good fighters, but perhaps no great fighters.
If he becomes the lineal champion and continues to dominate the division like he's been doing, it'll inevitably get him in the HOF.
If he does....well, what does that say about the boxing fans. Seriously, I don't think so. Even the average fan know Holyfield is past shot.
from the looks of it...he'll have to go DOWN in weight and fight people with pulses from the lighter divisions to become hof worthy.
Wins over Ibragimov/Chagaev, Valuev, Povetkin, Solis, a rematch with Peter and becoming the undisputed heavyweight champion will get him into the HOF.
Vlad is trying to unify the titles, but they will not sign for such. Vlad plans to fight anyone he can get, the best out there is possible.