Perhaps I mean anything might happen who knows! This is just a theory based on those pictures, although I've thought about the Elder's Eyes just being a normal Mangekyo and that just happens to be the design for his similar to the Rinnegan. That would actually make sense as well.
Or who knows. They say the sage was the greatest Ninja of all time, but all generations dream of their children surpassing them. Perhaps the elder son unlocked something higher than Rinnegan, like the Magekyo Rinnegan. This would fit the story too. Perhaps he fealt superior to his father and brother and expected them to be proud and choose him since he was the most powerful, but at the time of succession his brother was chosen for other reasons despite The elder's clear superiority. That would further explain the resentment.
It would also suggest that MR would be more difficult to obtain, and thus Sasuke probably won't wake up with them, but perhaps at somepoint during the fight with Madara... who knows.
EDIT- it's actually VERY plausible that it is something higher than Rinnegan since the tablet all the information came from reveals in stages of dojutsu. So since it was only read with Rinnegan so far that is all the info they have. Someone would have to unlock the next level up to be able to read that part of the tablet and learn the rest. Could definitely fit if it's a step up from rinnegan like mangekyo rinnegan.
Stone reveals in stages:
Sharingan
Mangekyo sharingan
Rinnegan
***Mangekyo Rinnegan might reveal unknown history thus far...