I think that Rockstar has already created a near perfect money making machine with GTA V and GTA Online specifically. Think about it: the game came out back in 2013(!) and sold probably around 30-40 million units on PS3 and 360 alone, most of them for full price. A year later, they release the same game again for the new consoles, again selling roughly the same amount of copies, again mostly for full price. Add on top of that GTA Online, which is still one of the most played and viewed online games almost 5 years post release, which has probably made them the same amount of money they already made by selling the game, if not more.
Of course other companies can't simply copy what Rockstar did, because R* have the reputation, ability and trust from their publisher to work on their games as long as they want. But if I were a CEO of a games company, I would at least try to imitate what Rockstar did with GTA V, specifically the timing of the release (right at the end of a console generation) and the inclusion of a seperate online experience.