Nothing wrong with OPs idea, not trolling etc. Just not sure how it would fit in believably.

We have a character with extensive (maybe) knowledge of future events, or if not access to machines/data about a possible future many generations later. Aka unless something drastically is different, we shouldn’t expect any significant losses, at least in our lifetimes. Or that our heroes will be victorious when faced with such odds.

On top of that, the first suffered its own cataclysm (warriors of darkness/flood of light), nearly ending all life as we know it (rejoining), so we literally just got done with averting the calamity to end all calamities.

From here, I do think the route is going to be whatever villains pop up want to end the world all together/destroy for the sake of destruction... but as said above we will just be victorious in stopping them.