Have to disagree here. Orochimaru will be forced to use oral rebirth to counter some of Sasuke's more basic techniques like Amaterasu and Susanoo arrows. Oral rebirth was shown to be a massive drain on chakra, and based on how sick Oro and Sasuke were affected after using it...I'd say Zetsu Oro gets about 7-8 uses (me being generous) before running out of juice.
Not seeing how Oro easily tanks/mitigates those attacks, when his only option when confronted with either one of those is oral rebirth.
Firstly, Sasuke would have to be exposed to the spores (a time-lapse jutsu) via contact with the air. There's no way spores are getting to him when he's behind Susanoo. In the event spores do latch on to his body, a Susanoo arm just plucks them off him. The fact that Sasuke can just hover in his Susanoo means that Orochimaru will never ever hit him with Kusanagi or scratch a V2 Susanoo given that his his sword couldn't pierce KN4.