To me, when I think "generational talent," I think of a guy that you can plop onto any team and single handedly see that team enjoy 20-30 more wins off his presence alone. Just a complete game changer.
Other than your fairy tale ideology of a player adding 30 wins to a team single handedly, Curry fits the mold of what you described pretty well.
Take Curry away and GS probably doesn't make the playoffs breh. His handles, playmaking ability and shooting are everything to that team.