So do you guys think TPP will span at least a decade,or will it be solely on the year 1984? Maybe the trailers have only shown the first few hours of the game. I'd like to have the game finish with an old white haired Big Boss with the horn out "who's age hasn't shown him down one bit" Just to see him age with all the stress and torment, it'd be so powerful. (Btw, how do you think the horn will come out?)
I think "The Phantom Pain" will primarily take place in 1984 as that is a nod to the novel of the same name and encapsulates the Orwellian themes that Kojima is trying to portray with the core game and it's story. We'll stay in that 1984 setting for most of the game, much like how Big Boss wakes up and is trapped within a world controlled by Cipher/Big Brother and having to respond to that. I think Big Boss will have to complete his "arc" that the game centers around in that era, and only once his transformation is complete and he's had that sort of carthasis that leads to his decision to create Outer Heaven will we get to see anything beyond that. Kind of like how Chapter 4 of PW ended with the "Call me Big Boss" scene and was considered an "ending."
This will be the "ending", as in it will be the ending to "the Phantom Pain" subtitle and the core experience of managing Diamond Dogs and so forth... it will be the end of the core game regarding Diamond Dogs seeking revenge against the man who we're lead to believe caused the Ground Zeroes incident, but knowing Kojima there may be an extra epilogue or secret chapter that goes beyond "the Phantom Pain" and moves into Metal Gear 1 territory and will have you controlling Solid Snake infiltrating Outer Heaven. That would obviously be set in the 90s and would need a time jump, and would be a nice bit of fanservice for the long time fans who want to see the timeline converge and the MSX games on the fox engine.
But if you're asking if I think the core storyline itself and Big Boss/Diamond Dogs will span a decade or go beyond 1984... Nah, I don't think so. I think outside of a time jump near the end we're stuck in the setting that Kojima has chosen for this story. I think if the main storyline spanned longer Kojima would have pointed this out in interviews, as unlike a "hidden ending" I wouldn't say it's a spoiler... it would just be a fact that they could use in promotion to tell us the game will go forward a few years every chapter or whatever.