Oh, interesting topic!
Based purely on intuition, I think the ranking could go something like this (from shortest to longest life expectancy):
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My reasoning:
- Ice flight is generally centered around preserving things, so why wouldn't Icewarden make his kin live a long time?
- A long life = a lot of time to explore Sornieth; Wind is generally portrayed as carefree / without worries - dragons from wind most likely don't have to worry about stress impacting their lifespan
- Not entirely sure about this placement; long life = a lot of prophecies to witness? more secrets?
- A lot of them do end up passing young, failing to withstand disease, but those who develop immunity probably thrive longer by Plaguebringer's design - keep in mind this is mostly supported by the fact that Plague is a magical element in Sornieth (they would be much lower if they didn't have magical abilities)
- Perhaps average, mostly based on where they live - could maybe be considered pioneers (settling down first in areas no dragons have settled before); could switch with Ice -> Earth flight is mostly about keeping track of history, so it would make sense Earthshaker made his kin live longer than the rest;
- Unsure, but I'd reckon they go hand in hand with Plague dragons, albeit only slightly lower; Fire flight is usually portrayed as determined and passionate
- If they fully follow Shadowbinder's teachings, they do love their pranks and causing mischief; might get themselves into trouble if their target is not so understanding
- Significantly lowered on account of their domain housing Luminax; otherwise, would score somewhere next to Wind
- If low magical ability = lower life expectancy, then here's where I would place lightning dragons (note: without auguments - they could perhaps lenghten it by using auguments + enhancements; something something innovation)
- A little bit morbid reason... good fertilizer for plants
- They do outnumber a lot of other flights, sure, but as an another comment stated, their magic might be unstable (pair that with the fact that they have... a lot of it)
- No natural magic; seeing as most of them are humanoids, they probably could live up to 100 years. I say could - we aren't entirely sure what their habits are / how they live, what their culture is. Tentatively putting them at the end.
Conclusion: Arcane Faes most likely have the shortest lifespan of all (Flight rising wise) dragons.
Feel free to make modifications to my list above! Like I said, I'm mostly going off gut feelings + emotions and not purely analitical evidence.