Konami should have just released a PES2023 SEASON UPDATE for the current gen. Then include some of the features (i.e. sharp kick, revamped controls, dribbling, new menu/font design etc) from the next gen into the current gen game, to prepare players for the next gen game. With regards to the gameplay, they don't have to do much besides make a few tweaks to make it different from the previous game e.g. make the pace of the game slightly faster, make it more responsive, make the ball feel lighter, make dribbling looser and so on. Pretty anything much anything that makes it feel like a new game.
I think this would take no more than 4 months to do? The large majority of that would be administration stuff like sorting out licenses and the database.