N'zoth wasn't mentioned in WC3, and Azshara only appears as a statue and a leader referenced in dialogue. The main elements of WC3 are the Scourge (still at large), the Legion (dealt with for now), the freeing of the Orc Horde (which was played out again in WoD), the fall of the Eastern Kingdoms (mostly stagnant with a few changes in Cata and BfA), and the awakening of the druids (which was pretty much concluded in WC3). In TFT, it's mostly Illidan vs Arthas (two characters which we thankfully seemed to have moved on from after Shadowlands/Legion) with a few interesting characters thrown in (Sylvanas, Kael, Vashj, Varimathras, Garithos, all of which have had their stories resolved, in some cases twice). Beyond further restoration of the Eastern Kingdoms and finally bringing the Scourge threat to a close, I don't see many plotlines left from WC3.