A stunt man's resume is pointing towards Grand Theft Auto 6 being in development at Rockstar Games!
An eagle-eyed NeoGaf user noticed that Tim Neff, a stunt actor, had updated their resume to include motion capture work for Grand Theft Auto 6 alongside Red Dead Redemption 2. Neff's resume can be found on both Resumes Breakdown Express and iStunt.com, both sites include the same set of games that Neff claims to have done motion capture work for.
Now, rumors of GTA 6 aren't new and while this could very well be the first legitimate mention of the game, it could also be a typo (the 5 and 6 on a keyboard are fairly close). Prior to Neff's resume mentioning GTA 6, a rumor in March of 2016 detailed that the groundwork for GTA 6 was being laid, though the developers had not decided on a location.
Later on in 2016, another GTA 6 rumor surfaced, suggesting that the game might be set in London. Another entry in the Grand Theft Auto series is inevitable, however, with Rockstar games hard at work on Red Dead Redemption 2, it's likely we won't be seeing GTA 6 within the year.