Milked GTA? I don't think you understand what milking means.
Gta4 released in 2008. 5 came out in 2013. That's 5 years between releases my friend. Far from milking. Rockstar takes their time and unlimited resources to craft huge game worlds and take many years to develop. I already can't wait for GTA6. It's certainly not a milked series.
With that said, I'd be a bit more excited for a Red Dead sequel.