Before I go any further, it's important to add that this is all a rumor so take this with a grain of salt...
With Red Dead Redemption 2 right around of corner many people have feared that Rock Star will abandon GTA altogether and focus on the new Red Dead. This is something that companies do all the time, so it wouldn't be out of the ordinary. But a GTA leaker going by the name of 2295 has said exactly that.
Whomever this might be has been pretty reliable for all of his/her leaks being accurate, but even 2295 stated this might change and nothing is set in stone. For now the updates are going to gradually slow down to prepare for Red Dead with Important/Export potentially being the last big update for the game. 2295 explained the staffing parts as wel,l with being four parts in Rockstar North, some are helping San Diego with Red Dead 2, some are working on the next GTA, and some are working on a classified game.
So with that big split it's going to be hard to run the GTA V servers with so little people. Last year GTA made seven hundred million dollars most of that money coming off of microtransaction, more than it made in its second year. They made more money than they did releasing it on PC. Rockstar has announced which shouldn't come as a big surprise that Red Dead Redemption 2 will mirror GTA V when it comes to the multiplayer with an open sandbox world.