We know that it is a bit far fetch but it is not impossible either if what we have heard about this Untold Adventures is true. We have not heard from CDPR yet but new rumors are suggesting that CDPR might be working on a new The Witcher game.
We know that Blood and Wine is the last time we will be playing as Geralt so if this Untold Adventure is really going to happen, we will not be playing as Geralt. Some people seems to believe that we might be playing as Ciri and that we will follow her through her journey across different dimensions.
If you played The Witcher 3, you would know that Ciri can travel through different dimension and when she was talking to Geralt about the different world she was hiding in, she did mention that she was hiding in a world where people own flying ships of their own and that they were all fighting wars from afar.
Some people believe that she was talking about the Cyberpunk 2077 world. So if we do play as Ciri and does follow her as she runs from the Wild Hunt, we may be paying a visit to the Cyberpunk 2077 world.
Of course, these are all jut rumors and speculation so take it all with a pinch of salt.