Since its in his path to acquire and know every jutsu in existence. Orochimaru and Kabuto formulated an hypothesis that in order to awaken the power of Rikudou, one need to combine the power of Madara and Hashirama. They even confirmed that Madara's Rinnegan was an testament and an confirmation of their hypothesis.
Madara even went futher to say that an "certain someone" had the same plan as him.
Just an loose opinion, I think Orochimaru and Kabuto recovered Madara's old body and modified him as said by Kabuto. Even Obito was shocked at this.
This could be why he pursued Sasuke's body.
Its possible Orochimaru knew that Sasuke and Naruto was the next in line for Ashura and Indra. Since Obito confirmed this information when he encountered Naruto during the 5 Kage Summit Arc.
Madara even went futher to say that an "certain someone" had the same plan as him.
Just an loose opinion, I think Orochimaru and Kabuto recovered Madara's old body and modified him as said by Kabuto. Even Obito was shocked at this.
This could be why he pursued Sasuke's body.
Its possible Orochimaru knew that Sasuke and Naruto was the next in line for Ashura and Indra. Since Obito confirmed this information when he encountered Naruto during the 5 Kage Summit Arc.