It's already pretty well established that a remastered Grand Theft Auto trilogy is happening. Publisher Take-Two Interactive said in August that it is working on three "iterations of previously released titles" that haven't yet been formally announced, and last week South Korea's games rating board let slip the classification of something called Grand Theft Auto The Trilogy—The Definitive Edition.
Rockstar has remained steadfastly silent about the whole thing, as is its way, but today even more evidence of a looming trilogy release bubbled to the surface in the form of a Rockstar Launcher update. @videotech_ of RockstarIntel found references to Grand Theft Auto 3, Vice City, and San Andreas—the games that will be included in the trilogy—in the update. A memory dump of the launcher.exe file posted on GTAForums confirmed the discovery.
It seems the new Rockstar Launcher update from today has began preparing for the new remasters for the GTA Trilogy. pic.twitter.com/qgqu9aegdLOctober 5, 2021
The data dug out of the update also indicates that previous reports about the updates being remastered with the Unreal Engine are correct: The titles found in the code include Grand Theft Auto III – Unreal, Grand Theft Auto: Vice City – Unreal, and Grand Theft Auto: San Andreas – Unreal. If you'd like to see the text strings for yourself, you can dig them out using any hex editor.
It's still not official, but I think it's about as close as we're going to get until it actually happens—and the fact that this Rockstar Launcher update contains specific references to the remastered games makes me think that it could happen soon. I've reached out to Rockstar for comment and will update if I receive a reply.