I posted this and this in another thread. I'm inclined to go with Theory 2. It's thoughts on resurrection and identities, which I feel align with her. Before La Signora, before the Crimson Witch of Flames, she lived as someone else. Who's to say she can't return to live as herself again, or have another identity? Fire is an element of resurrection (think phoenixes). She has pyro powers. Sumeru (land of wisdom, including forbidden knowledge such as bringing back the dead) and Natlan (land of fire itself) are coming, and attempts to resurrect the dead may be part of their Acts, which may include her.

She also "died" by Raiden's hands with no body shown. Where is it? What was the exact reason she was slain? The fandom's perception of Raiden will ultimately hinge on the motive behind her death imo. Given other leaks (of how the decree was started by the Fatui and other things contextualizing her oppressive actions) and how other archons are positioned as "allies/good guys", maybe there's more to this death than meets the eye. (Side note: If Signora forced Raiden to hand over her gnosis and she resisted, ending in killing her, this means the Tsaritsa and Raiden will have a feud to settle. The Tsaritsa needs all the gnoses in her goal, plus Signora is one of her most competent harbingers).

Tbh we shouldn't expect Mhy to pull off the most elaborate and cohesive storytelling, but the resolution of Zhongli's archon quest (where it turned out it was his plan all along) was a nice twist for me. Killing Signora and ending it at just that, despite her being key to many interesting future storylines, makes less sense narratively as it does financially (she has fans willing to spend for her).

Writing all this made me realize I really love her as a character lol. Maybe I'm just trying to make her death make sense in my head, but I really hope there's still more to her. Some characters, including prized 5*s, don't have the same significance in the main story she's had. You can say that's precisely the reason Mhy is offing her: she's not that central a character to be a complete loss, while also she isn't a nobody that her death won't be memorable to the playerbase. But 1) she had a team dedicated to creating her for months. 2) This is a fantasy story of infinite possibility where the plot can be explained away by magic and don't necessarily have to make sense. I will keep an open mind until there's definite proof - as in Mihoyo says it themselves - she isn't returning.

Will she be playable? I lean towards no. Will she come back? I lean towards yes