I've had this in my signature for more than a year that king killed ushimaru. Come up with your own theory
I also think that nidai kitetsu might be ushimaru's like you do but i have no clues for that so i decided not to add it so props to you.
Same purpose as the Nidai Kitetsu imo
Zoro vs King is almost set in stone at this point imo. Yamato is stalling Kaido for Luffy while Law and Kidd are with BM. At this point you have Luffy who will soon recover and go fight Kaido for the #time but there is also Zoro who get the magic medicine and now is back to full power. Also at this point we have every SH vs a tobi roppo or a calamity and in particular Sanji vs Queen... Zoro will take King while Luffy goes back to the roof. The only thing that is still in the middle is Marco and what he will do.
About the Shimotsuki I also believe he most likely is Zoro's father: master swordsman, face profile a lot like Zoro, Zoro's has big ties with Wano even if he doesn't know.. Oda could play the card that King killed his father, that wouod make King more relevant even because after Zoro fought onbthe roof King seriously needs something more but anyway if that happens imo Zoro will not be so pissed about it, maybe Oda could even subtly underline the guy is Zoro's father just to makebthe readers get it but Zoro doesn't.
About the Shimotsuki I also believe he most likely is Zoro's father: master swordsman, face profile a lot like Zoro, Zoro's has big ties with Wano even if he doesn't know.. Oda could play the card that King killed his father, that wouod make King more relevant even because after Zoro fought onbthe roof King seriously needs something more but anyway if that happens imo Zoro will not be so pissed about it, maybe Oda could even subtly underline the guy is Zoro's father just to makebthe readers get it but Zoro doesn't.
ushimaru is admiral greenbull