The ending of Resident Evil: The Final Chapter is that Alice survives because the antivirus only cleared the T-virus from her own body. The Red Queen then gives her Alicia's childhood memories, so Alice finally has a past. The antivirus will take years to spread across the world, and Alice vows to keep fighting the undead until then.
In my opinion, the memory transfer is the most interesting choice in the saga, because it answers a question the films had asked since 2002: who is Alice? It could be argued that it is also a retcon. Alice began as an amnesiac waking in a bathroom in Resident Evil (2002), came out of captivity changed by the virus in Apocalypse, and was one of many failed clones dumped in the opening of Extinction. Retribution then gave her a suburban housewife life with a deaf daughter, Becky. Revealing her as Alicia Marcus's clone means one scene has to patch a lot of history. Perhaps it works best if you read it as the Red Queen, the AI that guides her through the Hive, giving something back.
There is a neat piece of casting behind it. Ever Anderson plays both young Alicia and the Red Queen's child form, so the machine that has taunted Alice since the first film wears the face of the girl she was cloned from. That being said, Alice was created for the films and is not in the games, so this is the series settling an origin the games never had to answer.
The bleak part is the cost. Wesker drops his deadman's switch and destroys the Hive, Alicia and the sleeping elite in one blast, which removes the villains but leaves the world overrun. Isaacs dies twice in the same sequence: Alice kills him with a grenade, he revives, and a second clone who believes he is the real one kills the original before the undead devour him. It echoes the earlier reveal that the Isaacs she killed before was a clone, and it is a tidier piece of villain bookkeeping than Afterlife managed with Wesker.
There is no clean victory, only a cure already in motion. Compared with the cliffhangers that closed Extinction, Afterlife and Retribution, it is a modest, human sized finish to a loud saga.