According to Kojima, the scenes featured in the Ground Zeroes trailer and the scenes from Phantom Pain trailer originate from Metal Gear Solid 5.
Story details are scarce so far, but what we know is that the fifth Metal Gear Solid installment sees Snake in a coma for nine years before waking up in a hospital—presumably the one featured in The Phantom Pain footage.
To recap, there is no Phantom Pain, no Ground Zeroes–both these misleads were vehicles for MGS5 footage. The game’s full title will be Metal Gear Solid 5: The Phantom Pain.
Obviously, we’ll have more news about Metal Gear Solid 5 as the details emerge.