It is a matter of priorities.
Like Sagitarii says, including conversations and dialog for all possible worldstates after you finish the game would have been an enormous undertaking.
I would like anyone who thinks this is an easy thing of just keeping the NPCs around to think for a moment.
1) Every NPC would have to react to all possible world-states that affect them. For the major NPCs that would be all of them.
2) They need to have different scenarios of where they are and what they are doing, logically, depending on the endings.
3) Even entire areas might have to change dramatically if we were to showcase the ending world states
And this is just a small list of considerations that ultimately led to the decision to not include this. As is the case with branching stories, they get heftier and heftier the further you go down the branches. To add tailored content to the end world would be a huge a undertaking if we were to do it right (and we don't like to do things unless we do them 'right' particularly when it comes to story and plot).
And before you yell that this was lazy on our part...please remember that we already have one of the heftiest scripts in gaming and so many voice over sessions that it boggles the mind.
Just remember...there is never such a thing as "JUST" adding something when it comes to a game like this.
Okay just going to comment on this post. Which just seems to have taken the first comment where someone has given a reason for them not doing anything and gone with it.
That scenario was not what the majority of people have been asking for with this entire post. Hate to ask this, but did you actually read the thread? I think not.
What people are asking for, and sure some people did say it would be cool to experience an after end game state, but not the majority. The majority of people want the characters back in the game and concurred that a post Epilogue state of the game which would literally have not required any change, except the characters implementation.
Okay, now to move onto the presentation of facts and what we as a player base were asking for compared to this:
1) Every NPC would have to react... No, Every character does not know what happened in Skellige after the Epilogue, and only Ciri, Geralt and Avallac'h knew as well as probably Yen/Triss...
2) They need different scenarios, only three, and that's in the case of the Epilogue, without the post Epilogue, literally no work.
3) Entire area's need to change dramatically. Nope, post the Epilogue, the zones are still in a war-time state, the war is not over yet. The war ends, which entails these massive changes post the Storyboard, after the Epilogue. If you didn't do the Epilogue, nothing has changed because the story hasn't ended at all.
Sure, there is never such a thing as "JUST" adding something, but there is a thing as improving something to make it more enjoyable, rewarding and making your fans happy as well as satisfied with the end of the game. As well as being able to still feel immersed in the game world for DLC content, continuing their game.
I really hope that you make an effort to discuss this, and next time actually read the thread.
Because, for almost 250+ pages of this thread it has been discussed, the options you have and what would have been really, the best way to implement this change and it seems you have taken the one option no-one realistically expected and said, "Oh yes, we can't do this because... Or it would be extremely difficult to do this because..." when we already know these reasons and thus didn't make that a realistic option in the first place, more of a shiny dream enjoyed by some players...
The fact is that ending the game after the Epilogue was realistic and the best option to really conclude, Geralt's story. Your story board acts as a form of insurance for the player, to know that their character will enjoy said future, well also in the right time to have all the side quests still available, active and relevant, as well as all the characters deployed in the game world.
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I just wanted to add that I don't mean to be picky here or in any way aggressive, as I'm sure it reads, it's in my nature to pick apart arguments or words. But, I have literally been reading this thread since the first reply all the way through to now and have seen countless people come and give their opinion, opinions of feelings of the end of the game and then opinions and really interesting discussions about how CDPR could incorporate a solution realistically and achieve-ably. To have all that discussion take place and then to have a RED post literally addressing the only opinion we really didn't expect to happen, as being Extremely hard, and the way the post is made, as being not really an option in their eyes, is really disappointing nor does it feel like all the feedback has been thought about or taken in at all.