I was under the assumption that the Titans showed Nozmordu his future which started it all and then the Old Gods persuaded him to try and subvert his own death, the Infinite Dragonflight marched on to do that. There could be a lot on play with the Titans once again especially with how 7.3 plays out currently. I mean it was the Titans themselves that made Dragonflight, including them would be natural and I mean you could build a story around Nozdormu's struggle and the Infinite Dragonflight fruiting too then again overlap that with Old Gods too.
Who doesn't want to see an Infinite Chromie?!
The dragons have ALWAYS been important. Cataclysm with Deathwing don't make them anymore important than they should be, after all the Dragonflights have persisted within the game since Vanilla! Even the old World Dragon Bosses in Seradane, Duskwood and such are the Nightmare Dragons in the Emerald Nightmare raid!!! Ysondre, Taerar and co. Obviously Burning Crusade they weren't really needed and they aren't native to Outland so I don't see why they would join us when their charge is to protect Azeroth itself, walking away from it to Outland won't keep the World Soul safe.
In Cataclysm, they actually achieved their goal in protecting Azeroth and became mortal from it which does help us in killing Murozond in End Time.
They are still important now and why we went to Chromie's aid otherwise really we could shrug it off and be like "We got Legion to deal with, back off." We even before that went out of our way to help the Blue Dragonflight by healing Senegos, staving off the Nightborne Withered, helping Azuregos in Coldarra from Etherael playing with leylines inclusive of Nexus too and Kalec is part of the Council of Six.
If Deathwing alone can have an expansion then I don't see why Murozond can't either. The only issue with that is Murozond doesn't have the same destructive foreshadowing and ability to terraform unless he fucks the timeline and we are on a mission to prevent that. That would easily be sufficient and allow for a nice overall theme with intermissions of other themes from the said fissures in timelines, heck it could be a fucking awesome vehicle to display some of the lore within Chronicles that currently withheld in these books!
I dunno for me,
having all 3 threats in one expansion is wasted potential for future expansions. We also don't know who was at least responsible for Murozond's change compared to N'Zoth with Azshara. Granted that N'Zoth is the last one left, Y'Sharrj still managed to influence Garrosh beyond his grave. If Y'shaarj can do that while dead, the other two Old Gods can manipulate things while building it's physicality again.
They could actually use a Murozond expansion to then bleed into a N'Zoth and Azshara so easily and again make it a 3-4 year expansion set compared to 1-2 years and having all three. They did say that they could go to 2024 with World of Warcraft, having 2 expansions is by far better for the lore, story-telling and most important of it all; Profit.
https://www.gamespot.com/articles/wo.../1100-6423276/
https://www.polygon.com/2014/10/30/7...around-in-2024
They will extend the story as much as they can and actually (hopefuly...) try to tell the story properly. What I would like to see or something similar happening is:
Expansion #1: we go back to Northrend, dabble in dragons and the Lich King, he's already trying to push his luck onto the Dragons for his own way and maybe Bolvar is losing his humanity like Arthas was, we manage to qwell him for now. As we are fighting Bolvar/Lich King things get messed up even more for Dragonflight and is pushing Nozdormu further into the arms of being Murozond. Being near Yogg'Saron and maybe N'Zoth too slowly corrupts him and he turns into Murozond at the end of the expansion #1.
Exansions #2: Murozond goes a major trip and tries to actually enact his subversion of his death, he messes with timelines that causes the land to change and we fight to correct them because with the constant overlap of time, it's hurting Azeroth because in each timeline Azeroth isn't so good as the MU one. We manage to restore these pockets of time distortion until we finally nail Murozond. In all this time these pockets have allowed N'Zoth and Azshara to exploit our wayward glance and been trying to return to the surface with the Void. We slay Murozond and end expansion #2.
Expansion #3: With Murozond dead, everyone is recovering from the turmoil that he wrought and trying to repair the land and Azeroth herself since the time lapses have made it difficult, this has made her weak and then N'Zoth and Azshara ready their attack to try and help the Void claim Azeroth as a Titan for themselves.