There is an inherent writing limitation in games where you create your own character. Everything needs to be generic to a fit a character from every race, gender, and background. They would not be able to write as meaningful of a story if you created a cutsom character.
Think of all the colorful side-characters in The Witcher.... Dandelion, Triss, Zoltan, Yennifer. None of those would have any history with a custom character. And since their relationship with us would need to be generic they would have very little role aside from being a quest-giver (think "Roche" in Witcher 3 vs Witcher 2.)
I think Witcher fans would notice the diferences in writing right away. And besides, other members of this forums have vocalized as much before. See the "World of The Witcher" thread.
You can still allow the players to create a custom character and still not make the game world "generic". Bioware did a great job of this with both the Mass Effect and Dragonage series where you can create your own custom characters and not just determine their appearances, but their backstories as well and it would be reflected in the game.
At the very least the player character can be "predetermined" a la Commander Shepard but you can still customize the looks and combat style so that each "Commander Shepard" or in this case each "Witcher" will be a unique creation of the individual players that created him or her.
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I would like a Witcher 4, but as far as I am aware, CDPR are not even thinking about making another Witcher game in the near future.
If we're not playing as a Witcher, why would the game be called Witcher 4? Plus I don't see how the game would work if we could be a Witcher, a Sorceress, or a soldier, considering they all have very different jobs in the Witcher universe. It's not like Dragon Age where you can play as an elf or human and still have the same story. It just wouldn't be a Witcher game if I was playing as a sorceress rather than a Witcher.
Titles can be changed, that was just some ideas off the top of my head. Perhaps as the player character you're an adventurer with some inherent magic powers, who stumbles across an old school or runs into an old character who was one of the first ones to make the original witchers.
Again I don't know about this. Most Witchers seem as though they don't want their schools to continue. So many young boys die in those trials, I'm not sure re-starting them would be a concept that most Witchers would accept. Especially not the remaining Wolf Witchers. (Lambert would never agree, from what I can tell).
Personally I would prefer the next Witcher game to have Ciri as the protagonist. However I don't know if that would be possible either.
That would be part of the main story. Yes, the schools do have a high attrition rate, but with so few Witchers out there there can be more monsters and the monsters are getting braver and meaner with fewer and fewer witchers to actually go out and hunt them. Sure the villagers can make mobs and the local lords can send in groups of soldiers out to go hunt some of the various monsters but as you can see from many of the Witcher 3 contracts many of the "normies" that went out to try and kill these monsters, whether it be for fame and glory, or just wanted to get rid of something causing trouble for their town and village and died horribly.
Eventually people come to the realization that Witchers are needed, and even though they may be "mutants and freaks" and even though the process to recruit them can be pretty horrendous, Witchers are a vital part of the World.
Part of the main quest can even be working with various druids, mages, and alchemists to try and make enchancements and mutations the boys go through safer. While there may not be 100% success rate, there should definitely be ways to improve on the Wolf's School odds of 3/10 success rate.
