If you go through Radowid's assassination and don't side with Roche when Djikstra turns on the Temerian resistance (to be fair, from a Northmen perspective, Temerians had gone full Vichy at this point), Roche et al are killed, and Djikstra will eventually reveal himself to the public, and take over the effectively leaderless Redania as it's Chancellor.
If you didn't bring Ciri to Emhyr and Djikstra lives, Emhyr looses the war and is ultimately murdered, probably by the wealthy merchant guilds. Nilfgaard retreats, while Redanians chase them all the way to Jaruga river, absorbing every country as they go, forming the Northern Empire. Ultimately, Djikstra is described as laying down foundations for a strong and prosperous nation, though often through brutal means such as forcibly resettling people from various corners of the North to break local prejudices and solidify his rule. The world is ultimately divided between the "Blacks" and the "Reds".
Ciri gets to live in peace, leading a life of a Witcher. One of the game's ending scenes is in fact Geralt commissioning one of North's greatest swordsmiths to forge a new silver sword for her.
