Textures and models being recreated does not make the entire game a "remake". It's pretty simple, is the game being built on top of the original game? Is it the same game at its foundations? Is it a port with upgraded assets? Then it's a remaster.
They're not rewriting the code from scratch, it's the same code, it's the same game.
Misconception a game doesn't need to be done from scratch to be a remake as a remaking is modernizing the game for newer hardware Black Mesa is the same game as HL yet still a remake as is HL Source. To even quote the definition: https://en.wikipedia.org/wiki/Remake
"A video game remake is a video game closely adapted from an earlier title, usually for the purpose of modernizing a game for newer hardware and contemporary audiences. Typically, a remake of such game software shares essentially the same title, fundamental gameplay concepts, and core story elements of the original game. Remakes are often made by the original developer or copyright holder, sometimes by the fan community. If created by the community, video game remakes are sometimes also called fan game and can be seen as part of the retrogaming phenomenon."
XBC from what is shown has a new engine, textures, models, redone environments and new lighting as part of modernizing it for newer hardware.