That was a a NEVER going to fly. Reprint the core books with new art and it would be labeled a soulless cash grab. You'd have to change the book to account for the new art and the minute you touch the PHB, people are going to demand functional errata. Races at the very least would need to be redone to have the ASI and proficiencies removed to match the MotM style of design. People would want the Fizban Dragonborn or the Tome of Foes tieflings. And then people would whine and complain they didn't fix the monk, the beastmaster, the sorcerer, the moon druid, etc. They would want the Tasha additions made core, and the level 1 feat added to the base backgrounds. And that's the bare minimum.
They could reprint the 2014 PHB as is with a new cover, but they minute you tinker with the pages you're going to get "5.5". Your options were a Core Rules Slipcase set with gold foil covers and exclusive new DM Screen art, or some type of 5.5.