Actually, I think Sprawling is a Kuriotate civ trait, not a Cardith leader trait. You can't lose it.
I believe you can loose the trait, but it is simple to stop that from happening.
My opinion is that Cardith, having lived with a dragon in his skull for an extended period of time, learns enough to act as Eurabatres would. Even without the dragon, the leadership is still there.
Possibly.
I think he made most of the decisions on his own anyway, and that the Dragon only got involved when a harsh and decisive decision was needed quickly. He would probably start aging again once the dragon has left him and he might not always make the best and fastest decisions anymore, but he would still be as capable as any other leader.
Otherwise, it's possible that Eurabatres just can't be killed. His body might (nay, it will) die, but his mind is immortal. Killing him the first time just makes it so he can't regain his body anymore (or, at least, for a very very long time). This has some lore connections, since Auric resurrects Drifa, who could have potentially died at the end of the Age of Ice. Perhaps dragons can only truly die from a god's/demon's/angel's hand.
Seeing as how he had to find Drifa's bones to resurrect her, I'd say it is pretty clear that she did die.
I tend to think that Dragons have immortal souls, just like angels, gods, and humans. The soul would probably end up in the vault of the dragon's god, and could be called back with the god's permission after taking time to heal.
In my version, I plan to make the death of any Dragon create a Dragon Bones Improvement and a source of mana of the appropriate sphere. The randomly spawned Dragon Bones improvement would provide Ice Mana instead of Ivory (no more elephant trapped in the bones), and would be able to connect these mana types. Each civ with a dragon could revive their beast through a spell cast on the improvement with the right resource. There would probably be rituals that are a prereq to this, as well as rituals needed to build the dragons in the first place.
There are a few things to try to fix first though. I'm not sure how to make sure the Dragon Bones are not created if the dragon is captured instead of just killed, and there is the problem that in scenarios random resources would delete the ice mana under the bones.
Thats something I've been wondering, though its probably been answered somewhere. Which gods made which dragons, and does whoever made Eurabatres have any control over her now?
Abashi was created by Ceridwen, the Goddess of the Stars, Sorcery, Connections, and Pain. I believe that Ceridwen chose to release the beast (probably in responce to Sheiam rituals) and lend her to Tebryn Arbandi, allowing him to inscribe her forehead with a rune that will resurrect the runecaster until it is dispelled (which would require killing the dragon first, making Tebryn practically immortal).
Acheron was created by Bhall, Goddess of Fire and Passion, to be a holy weapon against the forces of Mulcarn. It is stated that he bit his mistress's hand when he was first created, so he presumably fell and become evil long before she did. He managed to break out of his prison by channeling the passion, rage, and hatred of a group of orks. He now serves only himself.
Drifa was obviously created by and loyal to Mulcarn. She seems to have some doubts about Auric, but after being fed Tasunke agrees to serve him. She would be unquestioningly loyal if he were the god of winter again. She was specifically released by her god, at least twice.
Eurabatres was created by Amathoan, the God of Creation, Fertility, Inspiration, and Genius. I believe that Amathaon was the first to come up with the idea of creating Dragons, and that Eurabatres was the first dragon ever created. He is certainly the strongest. He is the prototype, and all other dragons are pale reflections of his glory. The Golden One is the strongest being any god (except The One) ever created, which means he even exceeds the power of the strongest archangel, Cernunnos. I'm not quite sure he is still stronger than Cernunnos now that Cernunnos is a God, but it is possible. Eurabatres had no assistance in breaking out of the place where he was stored. His breakout is entirely from his own strength of will, and the rituals to recreate his form are probably of his design as well.
It is unclear what influence Amathaon has on Eurabatres. Amathoan is an extremely gentle god (who prefers butterflies to beasts), and did not want to get personally involved in the godswar. Eurabatres was probably made not to fight by his side, but instead of him. His god probably put a huge portion of his own power into the beast, considerably weakening Amathoan. I think the god did not want to face the horrors of war himself, so he pretty much gave his dragon free reign to do whatever he wants without having to report back on his actions. Eurabatres is used to commanding, not being commanded. He was the most powerful and relentless weapon against the taint of Agares, whose sphere is the opposite of his. Eurabatres would likely still heed a direct order from Amathaon, but Amathaon is unlikely to give him any. It is possible that Eurabatres relationship with this was rather like that with Cardith. I'm thinking that Cardith is generally in charge, but he is a kind and gentle soul who sometimes prefers to put the dragon in charge in order to avoid making tough decisions that require a little cruelty. Perhaps Amathaon acted likewise, treating Eurabatres more like an equal than a tool.
These are the only dragons we really know about, but there were more. The other dragons were weaker than these, and most fell in the Godswar never to rise again. Most of those who remained were slain by heroes in the age of magic, and the rest will probably never escape their storage dimensions. Some gods created many dragons, while some made none. I tend to think there were quite a few other Red Dragons, but there could only the one Golden One.