If they get the engine running properly on the Switch, most assets won't have to be touched. It's not a Wii port where most textures have to be upgraded. The higher resolution alone (when docked) and some antialiasing would be enough to enhance the graphic quality a lot, the smaller display (undocked) would hide a lot of unwanted artifacts while delivering the same performance as the Wii U version.
Tetsuya Takahashi himself has said the scale of the game makes a port unlikely. It's time and money that makes a project of that size difficult and we've heard that from the game's director and the head of the studio that made it. I get people want Chronicles X on Switch - I'm somebody who would love to see it on Switch - but it shouldn't be difficult to accept that it isn't happening this year.
He said "It's a massive game. Re-creating it would be really difficult."
That sounds like a more ambitious approach where they upgrade most of the assets (similar to the Crash Bandicoot and Spyro trilogies or Windwaker HD).
But a simple port of the engine with the same resolution (undocked) or a bit higher resolution (docked) would be good enough for many Switch gamers. And for these kind of ports you don't need the creativity of the original team, it can be outsorced to a third party developer specialized on porting games.
Additionally, even if it would be an easy port... it would be stupid for him to admit that in an interview for two reasons: he would start rumours of a port long before Monolith is ready to announce it and a "difficult port" is much easier to sell for full price to the fan base.
Last edited by Conina - on 03 February 2019