let me say this, it is almost impossible to be equal to what the sage was before he became a jin. now they could become more powerful than he was before becoming a jin by becoming the ten tails jin themselves, but then they would still be weaker than he was when he became a jin, let me explain. see the sage was the first person born with chakra, the only person comparable was his mother and she had eaten the fruit, thus you have him. when the sage split his power between his sons it was the first degradation of his power. now the sage did share a bit of his chakra with presumable everybody else in the world so at least others had chakra. but comparably to the brothers everybody else was insignificant in power. so when they had children there power would have been degraded generation by generation, which is why you have the sharingan, and most likely byakugan as well. they would be a mutation, because of the mixing of their bloodline with others. they would have continued basically until you get to hashi and madara's time, or at the very least until you have so many that you then decide to have a clan. even them most would have married outside of the clan with allies, so still thinning the bloodline.
Basically what that means that even if you take to of the most powerful senju and uchiha of their generation and put them together it's still only a fraction of what it would have been if say the sages sons had combined their dna in each other. the easy way to understand is take a mixed couple and they have a child, that baby most likely is gonna be somewhere in the middle of what both parents are as it takes genes from both lines. now take that same child and have them procreate with a one of the ethnicities from their lineage, and keep having the offspring only have children with that ethnicity. there will almost be no trace that anybody in their line was ever mixed, because the other genes it has over the years would overshadow it. now apply that with senju and uchiha and you can get the picture. no matter how powerful kabuto thinks he is, he's nowhere near like the sage, and sasuke is nowhere near that level either. now they can have more skill then he did.
now the onlyway somebody would actually be comparable to the sage is if they ate the fruit and then had a child. that child would be more powerful than the sage though, but you should get the point.