"The old days, when the games were offline, the experience was defined by what's on the disc. You had a distinction between a Prologue and a full GT, it was very stark. When the game becomes more of an online connected experience, that distinction blurs. This will be much more than a Prologue type experience."
It's pretty damn obvious that, whatever GT: Sport is or what comes after it this gen, this will be a DLC-expanded experience that will likely be the only GT game you have to purchase with the rest being expansions for the same experience.