I agree. I also remember that there were always eggmines close to the Northeastern coastal towns. (There's an eggmine in Gnisis, just northwest of Khuul, and I think there's one near Ald Velothi but don't quote me on that)
Also, another magelord that could have survived would be Baladas Demnevani. He would have been far enough from certainly Vivec and from Red Mountain to have time to teleport himself to safety. I can now imagine it. A bunch of Dunmer eggminers are probably cultivating crops in the Hirstaag forest while Baladas and Divayth are playing Volleyball on top of Karstaag's Castle.
It's nice to think that Divayth got away, but I have the feeling Landfall and subsequent disasters might have struck so suddenly that even the mages might not have been able to react in time. The moon hitting Vivec City that close to water would have sent up tsunamis right away, I think; and then you'd probably have earthquakes, not just a volcanic eruption. I guess the main factor for survival would have been distance from the impact site.
At the same time, I hope some of the netch herders and their livestock could have survived and fled. Hopefully entire species haven't been wiped out; I'd like to hear if that occurred, out of curiosity.