I've only tested that the "Flesh for Sale" will activate as long as you don't do anything concerning "Following the Thread" quest.
I also tried finishing the former quest before going to the last altar and kill the people there which triggered the latter quest.
It's still a bugged quest like...
They could actually change the trigger in way that you need to talk to Crach first before going to Faroe Island or something to continue the "Following the Thread" quest.
But I'm not a game dev and I don't know what else might break if they do something like that.
Good, all this Shani, Triss, Fringilla. Essi deserved a bit more than that end.
She could have moved to Kovir or Poviss but no. All we can do is remember and give a little dedication.
Still I love Yen more.
Guys please don't forget about Essi. Geralt also slept with her.
She confessed her feelings for Geralt but he said he could not reciprocate what she felt for him because he still loved Yen.
NG+ won't be a DLC, a future EE or maybe an attached feature on the next expansion.
There are already some NG+ items in the base game so we know it will come.
I went true neutral and Shani in TW1. Then read the books which shaped my decisions in TW2 (was disappointed Yen was only mentioned and in flashbacks).
That's the problem of knowing the background information. I should have avoided the books.
Geralt is much safer in Yen's ending since he might still die in one of those witcher contracts and since he already died once Yen isn't taking any chances.