My prediction.

So there are three

Firstly Yuki will die from her cancer and become the cursed spirit of maru. Fulfilling her Rika arc and be used to fight against her brother.

Then tsurugi will fulfill his role as kenjaku arc. He is already finding ways to optimize his little Curse energy so he will find the key to the merger and release it.

This will be yuji's chance to die and fulfill his gojo arc.

This is just my view on how gege has set up all the story events so far.