Yep, agreed completely. Ciri would be overpowered and since one of the W3 endings is Ciri "not coming back", I don't see how she could be the main character, and nor would I want her to be. I want to play as a male Witcher.What I mean is, players who descided Ciri to be the empress, or don't coming back wouldn't be satisfied with that.
Let's move a few decades down the road - there will likely still be heavy political goings-on with Nilfgaard, ideally some new sorceresses / mages / rulers.
What they need to do is come up with a story that triggers the need for more Witchers, obviously.
Wouldn't mind seeing our Witcher be the son of someone famous as well just to give things a twist / give the character some notoriety.
Or maybe even go in a different direction - have a Witcher created in a corrupt manner where a group of mages / evil organization just want to create a killer / assassin / professional fighter for some nefarious means, but perhaps his conscience overrides those intentions, and he escapes and then finds himself somewhat lost in the world, hated because of his mutations, but trying to survive and make a life for himself and eventually finds himself in a situation to take a contract issued by someone important for some significant coin and realizes that is probably going to be his path and insert main story characters / story plot at this point that he gets pulled into. (I'm just throwing out origin story ideas)
Feel free to share your ideas as well, I'd be interesting in seeing what other folks have as ideas for an origin of a new Witcher.
Also just to add in the event CDPR is reading our crazy ideas - just another side idea - if they are even at all thinking of using Geralt as the main protagonist for a follow up game - they could always build a 3rd DLC package following up Blood & Wine for W3 with the sole intention of setting the story in motion to sort of "prep" for the next game.