It's pretty much been the sole storyline in TNG and DS9.
DS9, yes, but TNG has also included Losing the Peace, Indistinguishable from Magic, and Cold Equations.
I didn't really see Indistinguishable from Magic as a pure TNG novel
What does "pure TNG" mean?
and we don't have Cold Equations yet. So most of the TNG output recently has been related to The Typhon Pact.
Ah, but by your logic re: "pure TNG," I don't think Paths of Disharmony is "pure" Typhon Pact. It only featured the Tholians in a short role at the very end; most of it was a standard TNG adventure set on Andor.