I've come to the conclusion that it won't be the Rinnegan. At least not properly. If it is then it just means that the gaining the Rinnegan from the Juubi directly is correct. But I feel like the Rinnegan is a purified form of the Juubi's eye. Also this will likely help prove if the Sage was a hyuuga uzumaki hybrid. So with regards to both these theories it won't be the Rinnegan but it will tell us everything we need to know.