WARNING! Contains SPOILERS for Fantastic Beasts: The Secrets of Dumbledore.
Credence/Aurelius identity twist - however, this comes with some tragic news.
An Obscurus is a parasitic force that acts as the manifestation of repressed magic in a young witch or wizard (young as they usually don't make it past the age of ten). Grindelwald figured out Credence must be a Dumbledore when he connected his case to Ariana's. The Dumbledores' sister had repressed her powerful magic all her life after a group of Muggle kids viciously attacked her for being a witch. She died when she was 14, but not because of the Obscurus because of a three-way duel between Albus, Alberforth, and Grindelwald. Credence is the only known case of a young adult surviving the Obscurus, but in Fantastic Beasts 3, he was said to be slowly fading away because of it.
When Credence confronted his uncle, Dumbledore saw the signs that Credence was dying (as he later told his younger brother, the phoenix bird behaved around Credence like Ariana's did around her). In fact, Albus even used an ashy phoenix feather to convince Aberforth (who was so hurt by the tragedy of losing Ariana and his mother that he was reluctant to meet Credence) that his son needed him. As the brothers made their way to Bhutan, Aberforth asked Albus, "How long does he have?" but Albus was not heard replying. However, earlier in the movie, he told Newt (Eddie Redmayne) that Credence couldn't be saved, "but he may yet be able to save us."
Does Credence Die At The End Of Fantastic Beasts 3?
Credence arguably saved Newt and his team by exposing Grindelwald's lies in front of the people who had just been manipulated into voting for him (via a charmed dead qilin). But Credence used his last strength to do so, collapsing under the ever-more-threatening Obscurus curse. Aberforth found him after Grindelwald fled, and when Credence asked if Aberforth ever thought of him, he replied "always" (a clear hats-off to Snape's line, which came at just as tragic a moment like this one). Aberforth carried him down the many steps of the Bhutan temple, but Credence was pale and weak, his life nearly drained out of him.
It's safe to say Credence didn't have long to live, but this doesn't necessarily mean that he won't appear in Fantastic Beasts 4. Dumbledore said he couldn't be saved, but he didn't say his life couldn't be prolonged. Credence is a powerful Dumbledore, and he is now under the care of two others. Finally, Dumbledore has been known to twist words around and not let on as much as he truly knows. It's possible Albus and Aberforth will now do their best to help Credence live for a while longer, even if his death is inevitable. As Fantastic Beasts: The Secrets of Dumbledore has shown, Credence is a key character, who is thus unlikely to die offscreen. Fans are likely to see him again, albeit for a short time.