Replacements for dead dragons
It’s good to speculate, however, your candidates are unlikely, such as Livia, we know nothing about her, other than that she’s “maybe” alive? Maybe not. Try thinking about simply a dragon champion rising to replace the elder dragon, in the case of Zhaitan and Tequatl, well Tequatl grew in power, but he’s no elder dragon yet! The gods may or may not also embody some of these facets of power, they might be perfectly good candidates to fill the role. Another distinct possibility is the role just doesn’t get filled in. It’s very interesting to wonder what might happen, but Zhaitan is dead, nothing has risen to replace him as of yet. Also, keep in mind, no promises this is 100% accurate, but Elder Dragons are… err Dragons? Perhaps only dragons can replace dragons, but that’s just a rather simple logic.
Personally I’d like to see going back to Cantha revolve around usurping the Emperor as outsiders inspiring rebellion and giving the Kurzicks and Luxon descendents their sovereignty back. Likewise for Elona, you have Palawa Joko happily leading an empire of his own over the sands of a continent long since forgotten the ways of the Sunspear. So I’d like to see expansions to be less emphasis on the dragons, maybe chit-chats here and there, but more primarily focused on unique threats.