I've never been a fan of 'wiping out' a realm. Smashing their army, see their council driven before you, and hear the lamentation of their peasants...sure. If you can beat them, then chances are you don't need all their regions.
Even if they are reduced to just a Capital and a few rurals, let them keep their lore/realm if players want to keep it. You don't have to own the whole map to win. Honestly, if a good realm is being snuffed out, everyone loses. Even the realm who conquers the map.
I wasn't a fan of every war needing to result in the utter annihilation of the enemy, every single time. I'm not a fan of the opposite solution some seem to advocate sometimes, in that realms should never be destroyed.
After all, a realm can be snuffed out without "killing" it, and often migrants can help bring new dynamics to other existing realms to make them more interesting. Depends a lot of the attitude of the losers, really. A once superpower that is reduced to its core but allowed to "live" might bleed out to death if it was filled with players who like the superpower aspect of it and end up disappointed with the lack of options their new weakened state allows. Just as a group of migrants might leave if their identity was too clung to the realm that they lost and they fail to bond with their new one.
There's no really simple rule to predict how things will turn out. Many losing realms have died in the past not because their enemies were not ready to negotiate, but because they weren't. Losing realms are notorious for expecting a peace agreement that leaves them better off than the state they are left in, forcing the invader to utterly destroy them to put an end to the war. There has also been at least a few cases where realms went back into war as soon as circumstances changed, even if the ink on their treaty was still fresh. A attacks B and wins, B accepts to peace, the next day A attacks C, B declares war on A. A prudent realm owes it to itself, if it wants to go wage war on other realms, to make sure that the realms it currently wages war with will not be able to easily backstab them at the first opportunity.
