Throughout the Star Wars saga, audiences have learned that there must always be a balance between the forces of good and forces of evil, with the Jedi always fighting back the Sith and their nefarious ways. In the book Star Wars: The Last Jedi: The Visual Dictionary, information about Snoke confirms that the galaxy hasn't seen a true Sith Lord since the death of Darth Vader.
"Snoke is powerful in the dark side of the Force, but he is not Sith," the book clarifies. "That thousand-year lineage stretching from Darth Bane to the last Sith Lord, Darth Vader, was undone when Vader died destroying his mentor, Darth Sidious. The fulfillment of an ancient prophecy foretold the end of the Sith, but it never predicted the end of darkness."
***WARNING: Spoilers below for The Last Jedi***
This presents a variety of interesting clues about the state of the Sith in the galaxy.
We learned earlier this year that Snoke wasn't truly a Sith, yet The Last Jedi saw him demonstrating Force abilities we hadn't seen since Emperor Palpatine. This confirms that one doesn't have to declare their allegiances to either the Sith or the Jedi to fully embrace their abilities.
Additionally, the implication that Vader was the last Sith Lord means we shouldn't expect to see one pop up in Episode IX, as one doesn't become a Sith Lord overnight.
While at the time of the events in The Last Jedi there were no Sith Lords, it's possible that, depending on the gap in the narrative between the film and Episode IX that Kylo Ren could hone his abilities to the rank of being a Sith Lord, potentially even embracing a new moniker.
Now that Snoke is dead, it's possible that Kylo will choose to find a balance between ruling the military organization of the First Order while also tapping into his Force abilities to create something new altogether, neither Jedi nor Sith.
The death of Snoke doesn't necessarily prohibit Kylo from becoming a Sith Lord, as Snoke wasn't one himself, so he needn't be a master to Kylo's apprentice.
We'll learn more about Sith Lords when Episode IX hits theaters on December 20, 2019.
The Last Jedi is in theaters now.