Nowadays there is only one final event in the campaign (mortal empires, ofc) and is the chaos invasion. That event is lore friendly, the same as the map campaing at the turn 0.
My point is, that menawhile the game proggress, the map changes and in most of the cases, is not lore friendly when the chaos arrives, so why should be the events being lore fryendly?
I mean, for ex, lets supposuse that in turn 100 the dwarfs are almost over with only 2 sttelments against the green tide. Then a dice rolls and it can happen 3 things.
2. The uprising of the dwarfs with the last blood they have, fightng the green tide, so they can survive another 50 turns.
3. The green tide becomes a event and get diplomacy penalties like the chaos have.
I would love to see final events like nagasht, but i think it would be better if the game have dynamic events, so when a main faction is going to die, it could survive enoght time so you can fight then later in campaing and prevent a steam roll of other faction; Also, in the other hand, is the possibilitie of that tide becames in a recognized global threat with buffs and debuffs.
It could be also for the player, think about bretonnia. You are conquering all the map, and then you became the global event, with new missions like crussades and some other buffs, but you get new enemies and some debuffs if you doesnt keep your rhythm of conquest.