Afaik, the expansions will take place during the events of the main game, not after them.
I thought about that but I don't know, man, I've never seen an expansion that shoehorns itself into the middle of the main campaign. It's always an epilogue or a sidestory.
Re-reading what info is out there, I'd say the first expansion is just a few side quests that make probably only references the main story by talking about the war and stuff like that, but likely has no direct connection to Ciri or any other main character. The other expansion sounds like it's basically just a standalone minigame with no relation to the main game.
Expansions will be set before the ending so that's not a problem and they also said we would be seeing familiar faces from the past ! (Shani ? Saskia ? Iorveth ? )
You guys got links? I just went on a googline spree and there was nothing about them being set before the ending. Just mention that you'll be seeing the Man of Glass and "dearly missed" friends and going to Toussaint, plus the typical CDPR promises of delivering worthwhile content.
And, yeah, my immediate conclusion was Iorveth too. Explains why he's mysteriously completely missing from the game.