Resident Evil 4 Remake, like any game, has a beginning and an ending. It would be rather strange if it did not, wouldn't it? The thing is, the final cutscenes may be confusing for some players, especially those who did not play the original games or who discovered the series through the remakes. For those players, we have decided to explain the ending so that you can understand its implications for the future. Obviously, we are entering spoiler territory.
For much of the game, we have known that Luis was working with Ada to obtain a sample of Las Plagas, which they refer to as "the Amber". Near the end, we discover that this sample is actually a dominant Plaga specimen, like the one carried by Saddler himself, which allows its host to control other Plagas. At the very end of the game, Ada obtains the sample for her mysterious client.
During the game's epilogue, we see Ada speaking to her boss, who is none other than Albert Wesker. Incidentally, it is worth noting that Albert Wesker is not the A.W. mentioned in a certain document. Those who began playing the series with the remakes may not know this, but Wesker is the mastermind behind many of the events in the series. The product of one of Umbrella's many experiments, Wesker is a genetically superior individual who also carries a special virus that grants him superhuman strength, speed and endurance. By the time the events of Resident Evil 4 Remake begin, Wesker is already working for Tricell and is seeking Las Plagas to deliver them to the company that will serve as the antagonist in Resident Evil 5.
In this same scene, we see Ada betray Wesker after he explains his plans for global genocide. As in the original timeline, Ada will give Wesker a fake dominant Plaga, significantly delaying the villain's research into how to control them. Following the original canon, Ada will presumably deliver the dominant Plaga to the organisation to which Wesker once belonged. This unnamed organisation—which included Wesker's H.C.F. unit in Resident Evil Code: Veronica—was Umbrella's main rival during the early games in the series.
All of this suggests that we may not see remakes of Resident Evil 5 or Resident Evil 6, since the canon has ultimately remained unchanged in this respect.
