It depends on which Obito
Obito??? That guy who was weaker than Madara? The same Madara who was one paneled by Zetsu a guy who stated Itachi was invincible?
True Obito aka both eyes
Obito can use kamui to make Itachi's attacks phase thru him. While doing this, he will use his long-range Kamui to remove Itachi's head. GG
He always sad that Itachi was a problem for him. In anime and in Naruto movie 6...
Obito can use kamui to make Itachi's attacks phase thru him. While doing this, he will use his long-range Kamui to remove Itachi's head. GG
I don't think there is a way to predict the possible outcome.Itachi can take on Obito because of his superior strategies.