People would buy the crap out of a GTA: VC remaster. Personally, if it's only a remaster with no changes to the original game except the graphics and the compatibility, with the same gameplay and story and all, I wouldn't think twice about buying it. Grand Theft Auto is one series which has games with extremely good replayability. GTA V came out 5 years ago and people still regularly play it, and it was the 6th (or 7th) bestselling game of 2017. Think about that, a 4-year-old game in the top 10.
I still play Vice City sometime for nostalgic purposes, I don't mind the graphics. But if they do remaster it, I'm very positive it'll sell very well.