first of all thanks to paulbee to make me think on this with his theory..
ur theory was exactly what i was thinking..
1. thinking about nagato enthrusted his dream to naruto.
2. kishi suddenly mentioning madara going up for rinnegan.
3. i personally hope jiraiya's comment on minato sealing kyubi in naruto..
(i,e) probably minato knew naruto as the genaration of sage 2nd son.
and due to his physical endurability of naruto .,he sealed the kyuubhi.
taking the case of kakashi always been mentioned that he is not able to effectively use sharingan since he is not an uchiha..
madara might also face a similar problem with rinnegan if he gets..
which makes naruto a suitable candidate to use rinnegan..
this is just my speculation(since he may have both the physical attributes and spiritual attributes) from how i mentioned above
4. and i personally feel what itachi entrusted to naruto,
i,e- he gave some powers..
its the spiritual powers of the sages elder son...
5. thus combined all these naruto the bearer of rinnegan
minato knowing naruto as the genaration of second son of sage "who possess physical attributes" i,e to hold the kyubi ..and be a jinchuriki
and the power given by itachi to naruto which could be the spiritual attributes of the first son of sage..
thus combine both makes naruto equal to sage and he can effectively hold jyuubi and become to use the rinnegan too.
these are jus my thoughts..
just to add
its proved in manga that many sharingans controlled by danzou using shodaime's arm..
i,e: the physical body of senju controlling the sharingans of uchiha (since both are sennins sons)
which is an added fact...
probably in future regard with naruto it can happen as such is he comes from the senju race or hokage line as madara's says ... he can effectively surely control the eyes of rinnegan..
alas i got a great proof for naruto gonna get rinnegan...
1. nagato belonged to the uzumaki clan....
nagato's rinnegan was activated when he was in a shock state.. when parents was killed..
i say if at all the sage was also from the uzumaki clan..
which means that uzumaki's clan members are capable of activating rinnegan like nagato.. probably the reason for madara to kill uzumaki's.
naruto can now perfect rinnegan either by activating himself or by acquiring it, since we have already seen nagato use it very ease..
uchiha+senju = uzumaki(SO6P) ,,
also the chakra from kyuubhi will play a great helping roll for naruto if he uses it