The new trailer for Hitman is a very interesting journey through the many exploits of Agent 47 in the previous games, which constitute the future from the point-of-view of the Hitman beta. In it, we see some of the classic hits from his "future," from the assassination of Franz Fuchs in the thermal baths of the Hotel Gallard in Budapest to some of his other iconic moments.
What the trailer is trying to show is the journey that you're about to help Agent 47 begin. It goes through the 20 year gap between the prologue mission in the beta of Hitman that eventually leads to the Paris mission at the beginning of the new game. It grabs onto that nostalgic feeling, showing you some of the finer moments from the previous games, bridging the gap between the old and the new.