That the series will get a proper send off is likely an important factor to its fans, and the series is certainly deserving of the opportunity to bring its characters’ overarching narratives to their respective conclusions.
This first post-Kitty (Ophelia Lovibond) episode does not dwell on what her leaving means, but we do see that her departure does have an impact on Holmes (Jonny Lee Miller) especially but arguably also on Watson (Lucy Liu).