I think the key to Itadori’s growth is going to be him realizing he’s a variation on the cursed womb death painting experiments… which means he’s an advanced version of Kenjaku’s ambition to artificially evolve humanity.
For now, Yuji’s unique lineage is only exemplified by the abnormal physical prowess and his ability to be a container for Sukuna without losing control over his body. It’s almost like he’s got some of the traits of heavenly restriction despite the ability to use curse power.
Theres lots of directions this can go. Say Sukuna abandoned Yuji’s body and took all his curse power with him. Would that result in Itadori becoming essentially Toji Zenin but even stronger? Or perhaps most of Itadori’s curse power is (unwittingly) being consumed automatically to hold off Sukuna’s possession - implying he’s got a comparable amount of cursed power to Sukuna himself.
Either way the final act of all this is going to primarily involve Itadori, Fushigoro, Sukuna, Kenjaku, and (hopefully) Gojo. Itadori’s going to be somehow on their level by then.