The question then shifts to why this hacker is posting some early footage. You would expect the newer stuff to be immediately accessible without searching etc. This is allegedly the same guy who hacked Uber and called them out for underpaying drivers, so maybe he's trying to raise awareness about poor security or something.
my anecdotal experience from working on 3 AAA titles indicates that ErneX is spot on.
Most games really don't exist as a playable format until about 1y before release, there are separate gates for features and content; content/UI/Graphics are worked on until about 2 months before release. Nothing before 6 months even looks like the final product in most cases: just a rough outline.
Yea, I wouldn’t be surprised if the recent GTA5 upgrade on next gen consoles was just a port of the assets to the newest RAGE engine so they could playtest the initial GTA6 missions and gameplay mechanics on it while the next version of the engine is perfected and the assets for fake Miami are developed more.