Well, I'm a skeptic of the shinju story on the stone tablet... But supposedly if all chakra are one again a new chakra fruit will emerge, The only thing madara gained from absorbing the shinju is able to channel all the chakra from the people caught in MT Into his body and you know the rest...
First of all, I don't want to make out that such issue is a fact; it is just a theory of mine. Sorry if it seemed that way

_@:
Hagoromo stated: "when all chakra becomes one, a new chakra fruit will be created, and it will be the end of the world". That means that the merging of all chakra into one, is a required condition to grow a Chakra Fruit; yet there could be other ways to do so. For example: what Obito did.
Also, the thing on the top of the Shinju seemed like a fruit indeed (not fully grown, but a fruit after all).
Anyway, what is certain is that this matter is a mess, as Kishimoto's laziness for explaining so is :dead: