Since Lizzie and Josie didn’t actually know what the Ascendant did or where it came from, there was every reason to fear/hope they would spring Kai, and their evil uncle would turn up at the Salvatore School.
Legacies and Vampire Diaries fans have long been talking about a potential return for Kai due to the facts that the twins are facing The Merge, they recovered the Ascendant used to lock Kai away, and Kai is just too badass of a villain to be kept out of the game forever.