There are a lot of rumors about Vice City being Grand Theft Auto 6's setting, but a better choice would have been Las Venturas... if GTA Online hadn't already ruined it, that is. Las Venturas is Rockstar Games' fictional version of Las Vegas, one of the three cities which were included in Grand Theft Auto: San Andreas, and it would have been fantastic to revisit and expand in GTA 6. Unfortunately, thanks to GTA Online's constant stream of updates, returning to Las Venturas in GTA 6 isn't likely.
GTA Online has proven to be an incredibly successful product for Rockstar, and this is partly because the company has continued to add content and features into the multiplayer title since it released. Even now, over seven years since GTA 5 initially launched, Rockstar is still adding new missions, cars, music, and entirely new maps into GTA Online. The latest, GTA Online's Cayo Perico Heist, introduced new characters and even a new island to players. However, the reason players won't be getting Las Venturas in GTA 6 isn't because of Cayo Perico, it's because of the Diamond Casino and Resort.
The Diamond Casino and Resort in Los Santos opened up to players on July 23, 2019. GTA Online's casino allows players to gamble, own a penthouse, have access to both hidden and not-so-hidden missions, and (much like the recent Cayo Perico update) also brought a new Heist to GTA Online. However, nearly all of these things are activities players were allowed to do in Las Venturas back in Grand Theft Auto: San Andreas - heists and all.
GTA: Las Venturas Would Be A Great GTA 6
By introducing Grand Theft Auto Online players to a casino nearly a year and a half ago, Rockstar is making players jaded on the mechanics of gambling. Lots of GTA Online players visit the Diamond Casino and Resort regularly in order to try and win a free car (or one of the many other prizes on the casino's prize wheel) and it's likely that some are beginning to get tired of it. If GTA Online had never opened a casino, introducing Las Venturas as Grand Theft Auto 6's location would be seen as a new, exciting shift in both location and possible gameplay options. Now that players know how casinos work in the world of Grand Theft Auto (at least in this generation) they are less likely to be excited about a city environment full of them.
Of course, it wasn't just the casinos which made GTA: San Andreas' Las Venturas such a memorable location. It was also the different houses players could rob during San Andreas' burglary missions, and the way the city looked lit up with neon during nighttime, and the plethora of great missions and characters (including Grand Theft Auto's best heist mission ever) which all combined to make an enjoyable GTA setting. While developers could still inject enough new features and next-gen shine onto Las Venturas to make it a viable Grand Theft Auto 6 location, it isn't likely, and thanks to GTA Online's Diamond Casino and Resort, players will need something else besides gambling to really get them excited.