Please, pleeease hold on a minute!
Let's be a bit optimistic, shall we ??
How about the eruption not been as bad as first thought... after all, the eruption in The Lord of the Rings, did not destroyed Middle Earth !
Second, that Telvanni Wizard (forgot the name), that was already searching for a cure, could have found it eventually, could he not ??
So everything is well, when it ends well - slavery was abolished (but not erradicated) + House Redoran rules (but meets some resistence) + House Hlaalu fells in disgrace (but survives as always) + House Telvanni learns its lesson and stops being so xenophobic (but not entirely) and so on and so forth.
In my opinion, this is more according to life - hard, treacherous, unfair but always moving on !!
Bets wishes to all.