Solid question. Airship is busy finalizing the switch version of the game (which has recently been approved by Nintendo so a release date should be revealed in the coming weeks) and working on the patch for xbox and ps4 version. I don’t believe there’s been any talk of having Xbox One X or PS4 Pro updates to the game (I could be wrong). Also, with the game being a classic JRPG/dungeon crawler I really don’t think you’d see anything spectacular in graphics upgrades for those systems (HDR, etc).
If you haven’t jumped in yet I wouldn’t wait for an Xbox One X or PS4 Pro version. I’ve played it on my Xbox One S on a 4K tv and it looks and plays great.
(I don’t work for Airship, just a fan)