As much as I don't like the prospect of it, I think it must be Rin. There aren't any female Konoha ninjas that exist in CN that we don't already have other than Summer Kushina, who I really really doubt they would make a seasonal ninja. And it's even more unlikely we will get an exclusive new ninja that hasn't even been released in CN. So yeah, to me all signs point to it being Rin...again.