Simply, DQXIS is not a unique case, most of the good ports to Switch have a similar optimization work behind them, and many times if it is not highlighted in a GDC interview, in a DF review or in some official article, it is a thing we wouldnt notice because they are made so that you barely notice the difference. Within Square itself, to put it the same company, we also have the case of Life is Strange 3 in which they themselves explain several of the tricks and things that they redid for the switchport.
What went into making Life is Strange: True Colors on Nintendo Switch and how does it look so good?
www.square-enix-games.com
Personally, I wouldn't call this a remake/remade or a downpour. I would call it good optimization. It is a better term for these cases of very elaborate ports.
And I expect intelligent optimizations for ports to Switch 2, to a lesser extent thanks to the fact that the difference is smaller, but in special cases such as Alan Wake 2, GTA6 or any new CDProyekt game.