Metal Gear Solid V: The Phantom Pain has been on the receiving end of some great reviews since its launch last month, and it's still selling well, but this hasn't changed the situation between Hideo Kojima and Konami.
In a New Yorker piece called "Why did Hideo Kojima Leave Konami" they write that Kojima did in fact leave the studio on October 9, following some sort of ceremony to mark the fact that he had worked there for almost three decades.
The very same report also states that Kojima had a non-compete clause in his contract, although it expires in December. This means that he can't join any other company to do anything video game-related during that time.
It remains to be seen if a bigger developer/publisher picks him up (given the funds he needed to finish The Phantom Pain, financial backing might be appealing), or if he instead chooses to create his own studio like so many big name developers have before him. We await his next move with interest.