Rockstar's Agent is one of those games stuck in development hell. We will probably never get to play it (but it does have a better chance to land on our screens than say Half-Life 3.) We last saw a few images of Agent leaked online back in 2015, with the latest leak via Twitter showing concept art that looks noticeably different from anything we've seen before.
No, it doesn't mean anything, it might not even be concept art from the game, but we can hope.
“Here are some Agent concept art. #Agent #Bully2Info.” According to the Twitter account holder, they found the images on the GTAForums. I couldn't find said images, so I would take this leak with a big bag of salt.
I'd wager that if Rockstar does develop the game now for current gen machines that it will be a massive hit.