I remember back before patch 4 (where they introduced the druids) someone from Larian said that update would be the last one where our old saved games wouldn't be playable after the patch.
Citation needed. I'm positive they never said that. I believe what they DID say was that you could keep playing the old save on the older branch, and that their new patching process should require smaller-sized updates. Of course that there will continue to be updates which break save compatibility - there is so much missing in the game, loads of classes, races, features, and spells.
