On a related topic, here's some article about gender and gaming. Admittedly, they only asked teenagers, but there's a clear message.
Most male and female gamers don't care too much about the sex of the protagonist. Surprisingly, the desire of female gamers to play a heroine seems bigger than the need of males to play as males.
"70% of girls said it doesn’t matter and 78% of boys said it doesn’t matter. Interestingly, boys care less about playing as a male character as they age and girls care more about playing as a female one."
RPG's also seem to be a prime genre for female gamers:
26% played first-person shooter games like Call of Duty and HALO, 36% played role-playing games like Skyrim and Grand Theft Auto, and 17% played sports games like FIFA and Madden. (19% did not play games, compared to 3% of boys.)
http://time.com/3948744/video-games-kate-upton-game-of-war-comic-con/
While we of course don't know what will be in 5 years, female protagonists (and female gamers) are a huge topic right now. Especially in media not directly related to gaming (like newspapers). I would bet 100€ that a game with Ciri would get them more free media attention than a game with a self-created protagonist.
Don't forget that she would be perhaps the only female protagonist in the whole industry that has a deep background story. She might be a bit of a Mary Sue in W3, but she has a ton of flaws in the books. Which other female in gaming comes to mind who has a story that takes more than a 5 minute intro to tell?
We've all seen how hard they try to turn Lara Croft into a believable person (and mostly failed). Like many other female heroes, she carries the burden of having been portrayed as "sex doll" previously.
Can't really think of any other developed female character who could carry a game. Sarah Kerrigan is great, but wrong genre. Japanese games have some, but I never cared about final fantasy and Resident Evil, so I can't say anything about them. Alyx Vance in Half-Life would probably be a believable heroine if put in a mech suit like Gordon Freeman. Bayonetta is just too crazy a game to count. Samus Aran deserves a honorable mention for being a female heroine back in 1986.
http://www.complex.com/pop-culture/2013/03/the-50-greatest-heroines-in-video-game-history/
http://gamerant.com/tomb-raider-video-game-women-we-respect/
If they don't fuck her game up completely, she would
easily be on top of all those lists.