In the past David Hayter has denied having involvement with Metal Gear Solid 5: The Phantom Pain, stating that he is not returning as Big Boss. However, there is a theory that has been doing the rounds of internet which claims that he will return as Solid Snake. There seems to be no strong evidence supporting these claims however there have been several hints dropped by voice actors of The Phantom Pain, Hayter himself and sound files which were found in Ground Zeroes.
However, Hayter has tweeted that he is not returning to The Phantom Pain even as Solid Snake. When asked by a user whether players will be surprised to see him return as Solid Snake at the end of The Phantom Pain, Hayter stated that he would be more surprised than anybody else. So there you have it, Hayter is not returning even as Solid Snake in The Phantom Pain, that is unless you believe that he will return as David, before he got his code name: Solid Snake.
Meanwhile, Robin Atkin Downes tweeted to David Hayter about using fulton recovery. I leave that tweet to your imagination since this could mean anything.
Metal Gear Solid 5: The Phantom Pain launches this September.
No-one more than me. https://t.co/jMK7wMZSRP
— David Hayter (@DavidBHayter) June 10, 2015@DavidBHayter stand by Snake... Checking in with a friend...planning on using #FultonRecovery
— Robin Atkin Downes (@Robin_A_Downes) June 8, 2015