Bleach 642 spoilers have been released, and one of the neglected angles is how the religious symbolism is heavily emphasized.
Readers of Bleach would not deny that the manga is filled with religious symbolism. Bleach Asylum presented the general premise:
"Yhwach is clearly being associated with God/Yahweh (perhaps a false god). The Soul King Palace is being associated with heaven. Ichigo is implied to be Jesus or a Jesus-like messiah figure."
There is also the idea of the Shinigami being very Japanese, the hollows represented by Latinos (with Hispanic names) and the Quincy being German/European along with the Christian undertones.
After that is established, we begin to see how Mayuri, a mad scientist, is battling Pernida, the left arm of the Soul King, or better yet, the Hand of God (h/t Reddit user : EspHellion).
In this chapter, part 5 of "Baby, Hold Your hand: Eyes are Open" we finally get the revelation about Nemu teased in chapter 640.
The translation was correct, Nemuri Nanagou means the Seventh. For Christians, seven is recognized as a sacred number often attributed to divinity. The reason why Mayuri is concerned about Nemu is simply because she is his masterpiece; the fulfillment of his dream to make new souls.
Is Mayuri a god? No, as Reddit user "Tezzeret" responded: "Mayuri's attempt to do what the soul kind does is sort of like the typical depiction of a scientist researching cloning or stem cells 'in an attempt to be a god' or something to that effect."
The implication of these is that Nemu will die as the sacrifice to save Mayuri. It has also been pointed out that usually, characters featured in a flashback are on the way out. Would that prediction hold true?