Oh jeez, after reading this I've actually had to comment.
This is seriously a case of doomed if you do doomed if you don't.
What is asked for is pretty much meaningless or impossible, if CDPR would've put the characters as a shell in their former place (The Inn, KM etc...) but let them do nothing there would be just as much uproar.
What people actually want is the impossible to have a seamless "unending" content when the main characters scripts are still fully functional when the game and the main story has defacto ended.
This would not only require a metric ton of content, but is also an immersion breaker on its own.
The story ends with the epilogue, there is no place for neither Geralt or any other main NPC in the world as it is, heck considering some of the endings half of your main NPC's would've been hunted and burned at the steak, but in none of them do is see a place for them to just simply go back to their pre-end-game state as nothing has happened.
None of the endings in the epilogue really leave room for things to continue to go about as they were, Novigrad is in turmoil either because if the witch hunts or because of fall out of Radovind's death.
Every other main place has also changed greatly at least on paper by the events, and everyone seems to be moving on in the epilogue, and so should you.
The events of W3 changed the world, and every character, you can't simply say well put those NPC's in those 3 places based on ending A B and C and expect it to feel any better than how the world looks like now.
If anything how the world looks like now is more like it "should" look based on the epilogue the main fighting is over most life has been normalized, and life as you know it tends to be quite plain and boring.
As for the demands from CDPR to implement major changes to how the state of the end game, besides them being quite unreasonable they are also most likely not possible.
Any major change to the game will require creation of content, and most importantly additional voice assets, and here is where you hit a major issue.
The recordings for the game are done, and I'm about 110% sure that they are also done for both planned expansions as this is the norm with such productions.
Getting the actors signed up and recording the assets (in what 5+ languages) requires an enormous amount of resources that CDPR will not spend, and most likely can't afford.
Getting every major voice actor renewing their contract and recording new lines will probably cost more than i would cost to finish the development of the 2 pre-planned expansions.
Not to mention that any change to the end state of the world will also mean that a pre-epilogue world will be enacted this is an issue on it self which most likely leave just as many people unsatisfied / wanting more.
People would expect to see some outcome of their actions with Roach/Dij/Radovid, people would want too see this and that, there will never be a state which will satisfy anyone to any reasonable extent yet alone everyone.
So yeah while seeing and empty castle (like 3-4 NPC's with 2 lines will make it less empty) isn't that much to look at it's at least an ending, the baddies are dead, everyone else moved on, see ya next time.
And this pretty much plagues every open world game, you either get a world in which all non-generic quest NPC's have been "removed" and no one really cares for "who" you are since the main story is over, or you get a patchy world in which the main NPC's serve as trophies which degrades the entire plot of the game and any effect you had on the world in the 1st place.
I think a major backlash for this is because people still think of W3 as a 10/10 game while in fact it's just as flawed as the rest of the witcher game's and in some area's more than the others.
Every Witcher game was plagued by issues ranging from purely technical design constraints to the fact that in every title CDPR was treading into a new territory for them as a studio and without major financial support (they've almost went bankrupt between 2008 and 2010), and since I haven't seen a single good solution to the "open world" RPG problem I don't know what any one here expects them to be able to somehow magically solve it, as it might be unsolvable.
As for people screaming for a reply, what you need to understand is.
CDPR just shipped a game, shipping a game means that there will be a huge restructure within the studio, many people will leave, many will be reassigned, and most importantly many will be finally able to take a break which is a rare thing when you deliver software or any project on the scale of the W3.
You also need to understand that anything they might do has to be compatible with 2 main things 1) their current studio wide plan and 2) their current plan for W3, and the witcher franchise in general.
With all the technical and financial issues aside those 2 mean that there's no easy solution or a quick answer, this isn't something that they can decide to just do and wing it, and after just shipping a game there's probably no one person in CDPR who can or will commit to an answer other than "thank you for your feedback, we do not have any plans at this time".
As for the comparison with ME3 well people forget that:
A) It took BW a month to "reply", and 3 months to release an "extended cut" of a cinematic which didn't really appease anyone.
B) People have a very short memory but the "Citadel" DLC was released over a year after the original game, required a new play through and really was kind of a shitty DLC which didn't resolved most of the actual grievances people had with ME3.