I don't know if it is obvious enough that Sasuke will be given the Rinnegan but I figured it would be good to say it anyways. Here's my reasoning:
The Rinnegan is needed to summon the one-eyed demon statue.
The one-eyed demon statue is the mummified (drained of chakra) ten-tailed beast. The statue resides inside the moon. That is where the members of akatsuki have been meeting for the Illusionary Dragon Nine-Consuming Seals ceremony: on the moon itself. Obviously, only certain members can survive living there which is why the other members could only visit by projecting their chakra.
The blind-fold of the demon statue is hiding the one-eye that is a combination of the rinnegan and sharingan. Look at the image when the sage of six-paths is squaring off against the ten-tailed beast. The one eye has the concentric rings of the rinnegan with each ring containing the magatama shapes of the sharingan.
Madara took back the Rinnegan because he needed someone else to synchronize with the Demon statue since Pain was dead.
Madara is obviously going to use Sasuke by giving him the rinnegan so that he will perform the ritual instead. Sasuke is now the perfect candidate to resurrect the ten-tailed beast since he possesses both the sharingan and the rinnegan.
Nagato will eventually need to take back the rinnegan from Sasuke so that he can control the ten-tails beast.
And that's that. Naruto might have inherited the will of Nagato but he won't get his eye-balls O.O
Madara isn't trying to unite the six paths or anything as speculated by some. He really is just trying to reawaken the ten-tailed beast, control it, and then rule the world