I voted for sad but I like endings which have strong resolution in story and for characters. Players sometimes don't have to agree with it but they can understand it.
My question for all is: How to you like ambiguous ending, open for interpretation ?
Nothing is known about W4. But it would be good idea to have M/F unvoiced character to choose from with redesigned extended universe and lore, gameplay and new signs.
Though, I root for Guardians of the galaxy sci-fi type of game.
Witcher is a beast hunter. Witcher universe can be expanded and introduce new classes and creeds skilled with different weapons and magic.
Geralt can live in this timeline or it can happen 1000 of years after Geralt.