Any new novels still using things from the Litverse?

[Christopher]

Probably not as they were mentioned by name in Distant Voices (DS9).

Yup.

The Deep Space Nine Transcripts - Distant Voices

GARAK: Happy birthday. I know it's a few days off, but I wanted to give you your present early. It's a Cardassian holosuite programme. An adaptation of one of Shoggoth's enigma tales.
BASHIR: Is it? I see.
GARAK: You sound disappointed. I thought you enjoyed mystery novels.
BASHIR: I do. Human mystery novels. The problem with Cardassian enigma tales is that they all end the same way. All the suspects are always guilty.
GARAK: Yes, but the challenge is determining exactly who is guilty of what.

 

[Shamrock Holmes]

Though it might be fair to say that Una was largely responsible for developing the concept as the above quote is fairly scant on details.