Forgive me if I'm wrong, but I thought that Rockstar was the license holder to GTA? I don't think buying Take-Two would necessarily mean they'd get GTA, just like if somebody were to buy 2K Games, they wouldn't get rights to Borderlands 2.
Again, I'm not that sure how licencing works, but it's just a thought.
Take Two owns 2k and Rockstar they are subsidiaries