They have consistently done the second, which makes absolutely no sense to me since doing it right would mean they could bring great old games to a new audience. All they need to do is increase framerate caps (and fix bugs caused by that), increase render resolution, and improve texture quality. They should have all of the original files, so this shouldn’t require a ton of effort, even if the code is a mess.
GTA SA and friends was terrible because it didn’t look anything like the originals since it was a mobile port. Nobody asked for big changes, just a few QOO updates. The same is true for RDR, we just want to play it on PC with higher FPS and whatnot, we don’t expect anything groundbreaking. If it’s easier, they could port the campaign to RDR2 (they already have a lot of the models) and then not have to maintain the older codebase. Surely that’s an option too.