I presume the person walking into the tree at the end is...

[Perlmutter]

Obito. He will claim to be Madara, and he will say he is there for Orochimaru, because time wise, these fillers seem to be staying true to the story, and Orochimaru does join Akatsuki around this time after he flees. That or it is Sasori

 

[Queen of Saigon]

or Kakashi

 

[Hyuga Prodigy]

or Kakashi

This!!!!!!!!!!

 

[sLm]

It should be Jiraiya, because if I don't recall wrong, there was a fight between Jiraiya and Orochimaru right after he left the village, and we haven't watched it yet.