It is almost certain, that he would live longer. It is also possible that he could have a son. But it's only possible not certain and his heir at the moment is from legal POV still Mary of Anjou. With Louis around, Casimir could accept such a solution because Louis was powerful and his support was very important. But giving your country to the little girl with contested rights even to Hungary? That's another story and I doubt if Casimir would agree to this. He would rather name his grandson a new heir to Poland in case of him not having a son. Perhaps Casimir would make him even a prince of Galicia to secure support for Casimir of Słupsk among Polish nobility?
Why Casimir III should prefer his Silesian nephew over his grandson? And this nephew is dead at the time of POD so there is no possibility of him surviving. That's another topic.
Why? His Nephew belongs to the same Dynasty as his and his grandnephew’s claim is superior over Louis I’s claim over Poland.
Kunigunde of Kuyavia is the eldest daughter of Wladyslaw the Elbowhigh..
She was. Kenna passed away before Kazko could assume the throne. Kaźko would have to do something, if he wants to ally with Jogaila against TO. Although I would doubt it, he would rather ally with TO against Jogaila.
Depending on when exactly POd happens, maybe Kenna Joanna's death could be butterflied away?
Okay, you have a point in that, although the nobles might prefer his grandnephew who belongs to the same dynasty.
Kazko would have a better chance to succeed if Kenna did not die prematurely but that is not a part of the topic, I think if Kenna survives, the Polish-Lithuanian alliance would only last until Kazko's death.
Both were born after Casimir's otl death. You need Louis to die between July and November 1370 to leave only Catherine, or die without children earlier.
