The Cloud Serpents in Pandaria and the Stormdrakes on the Broken Isles deserve an entry. As do the Proto drakes most are still roaming Northrend.
It's a bit weird to say Chromie is currently doing anything, because Chromie as a bronze dragonflight is often many places and at many times of her life, as she's commented before about having met us already or if this is the first time, because she's constantly traveling through time.
Maybe a minor point, but Senegos is the patriarch of the Azurewing flight, which is distantly related to the Blue Dragonflight, not part of it. They split from each other millennia ago. It's not impossible he wouldn't help his estranged kin, though. It's odd you didn't mention Stellagosa here also, as she is also in charge of Azurewing and took on many responsibilities of leadership as her grandfather's health declined. I would put better money on seeing her having a large part in Dragonflight over Senegos, as much as I liked his character.
This is Stellagosa erasure! >:(Stellagosa is definitely the biggest candidate for the next blue aspect if there is one. She's Senegos's daughter and was instrumental in helping the Nightborne.
No mention of Zaladormu or Anachronos, the default leaders of the Bronze Dragonflight in Nozdormu's absences but you mentioned the game-mechanic-only Zidormi? For shame.
I know she's not a dragon, but the Bronze's warnings about Salandria and what her future self "may or may not do" is an extremely appetizing bit of lore to me. Throw in her obsession with dragons and desire to own one someday, and this could be one of best villain origin stories WoW has thrown out in a long, long time.
Big thing everyone is forgetting, with talk of Aspects:There are no Aspects anymore. Not since the end of Cataclysm.When the then-Aspects of the 4 flights (other than Black) used their power to kill Neltharion/Deathwing, it took all that power from them, be them the original Aspects (Alexstrasza, Nozdormu, and Ysera), or a new Aspect (Kalecgos). It is made quite clear that the Aspects no longer have the power they once held, in the post-battle cutscene in Dragon Soul.Are they still immensely powerful? Yes. But they are still shadows of their former selves.