As posted in a statement on Twitter, the moves were made "based on recommendations supplied by teams supervising the development of both games." The new target for the Cyberpunk 2077 upgrade is the first quarter of 2022 (January-March), with The Witcher 3: Wild Hunt's upgrade hopefully coming in the second quarter of the same year (April-June).
CD Projekt Red had been aiming for both of the major title updates to go live late 2021, but also approached marketing their releases with a reasonable degree of caution, given the events surrounding Cyberpunk 2077's release. In recent statements, for instance, CDPR emphasized that it can't be said with full certainty that their production schedule regarding the updates wouldn't be subject to change.
The story surrounding Cyberpunk 2077's rocky console experience has been well-documented, with graphical and performance issues making the game nearly unplayable for those on PS4 and Xbox One, while those with PC hardware have been able to go as far as make third-party mods that offer balancing, bug fixes, reworks and new content for all aspects of the title's gameplay.
For now, PS5 and Xbox Series X|S players will remain with the lone option of playing a backwards-compatible version of Cyberpunk 2077 until the free next-gen console update ultimately arrives.
Meanwhile, the community of The Witcher 3: Wild Hunt is in a similar boat with the postponed "visually and technically enhanced" free next-gen update of the game intended for PC, PS5 and Xbox Series X|S, aside from it also including new content inspired by The Witcher on Netflix.
Additionally, CD Projekt Red has mentioned that the situation for The Witcher 3: Wild Hunt is a bit different being that the next-gen upgrade there is being developed mainly by an external team in Saber Interactive.