I think that not including and expanding upon the the Broken Isles was a wasted opportunity during Battle for Azeroth.
From the Horde POV:
In Battle for Azeroth, I was a bit surprised how they spent some effort introducing the allied races (such as the Highmountain tauren and the nightborne), but never really seem to explore their actual settlements that much, in the Broken Isles.
I mean, if you look at any map, they were situated EXACTLY between Kul Tiras and Zandalar, and Azshara must have sent forces there to take the Tidestone to Nazjatar, which was also situated fairly close to the Isles. They should update both regions for Horde players at least.
The nightborne could easily have played a more active role in the Fourth War, perhaps even a staging ground against Boralus and the Eastern Kingdoms. Same for the Highmountain tauren, who could have further strengthened bonds with the tauren by inviting Baine's people to fortify their cities.
From the Alliance POV:
- Mount Hyjal might be better fortified than Teldrassil, but there's nothing preventing the entire Horde from bombing and burning down Nordrassil if push comes to shove (with major tensions and skirmishes still lingering according to Exploring Kalimdor). The Horde Council could easily marshal their combined forces to stage a massive aerial assault via zeppelins and airships, and Nordrassil becomes Burning of Teldrassil 2.0.
- The Wardens have existing settlements in the Isle of the Watchers in Azsuna already, and have Towers all over the rest of the Broken Isles. From the Battle of Darkshore onward, both Maiev and Jarod seem to be aligning themselves with the Darnassians fully now in any case.
- There could be a Highborne connection to Azsuna, the other ancient pre-Sundering magical center, perhaps with Mordent Evenshade and the existing Shen'dralar, something that might be better explored. I have no idea whether Farondis is aligned with the other night elves at present post-Burning of Teldrassil, but I liked him a lot as a character also.
- Tyrande has links to the Temple of Elune and the priestesses there, and Malfurion and the kaldorei druids to Lorlathil (his birthplace) and the Dreamweavers and druids in Val'sharah, many of whom he personally tutored in ages past. I think that the night elves were also responsible for growing Shaladrassil in the first place.
- The night elves literally have no capital or real home at the moment, they might as well find somewhere closer to the Eastern Kingdoms, where the Alliance can perhaps support them more directly, rather than in Kalimdor, where they are in honesty, very badly outnumbered, outmatched and surrounded by enemies on all sides. Teldrassil is yet a smoking husk, the kaldorei can never truly win their guerilla wars in Ashenvale and Azshara, Feralas is heavily contested territory at best, and even Darkshore is pretty much lifeless and abandoned after the Fourth War, with Bashal'Aran in ruins once again.
I mean, if the Dragon Isles are now being explored and Tyrande is apparently playing an important role, they might as well do something more in-depth with the nearby Broken Isles and give the night elves something new and interesting. I personally liked Legion and the gameplay there a LOT as an expansion overall, and I at least don't want them to be forgotten like the draenei and blood elf starting zones for over 15 years now.