I know the truth. Mr. Kojima is playing with us(fans). This Rising thing is an Extra VR Training that you can play in the real game MGS5.
He did it on MGS2, and now is doing it again, always Metal Gear have surprises and this one will be the biggest one.
MGS5 will have Big Boss as the main character. Kojima will never let down his masterpiece with some garbage proyect like Rising.