There have been predictions from sanji fandom that sanji would become the next ruler of Germa kingdom at the end of the story.
However, latest chapter just hinted for sanji's upcoming death at zoro's hand
Just like how zoro made a resolution over kuina's death, he might make a resolution for sanji's death here too. To pay respect for his former crewmate, zoro would marry his sister and become the ruler of Germa kingdom.