I mean, thanks to her exceedingly bare-bones lore _(which has ALWAYS been bare-bones, even before any retcons)_, all she's got going for her is being the mute girl who plays music in Demacia.
Now we have Aphelios, who is also mute and is another Lunari champion that people have wanted for some time now. So now Sona doesn't even have THAT going for her.
All the new Demacia lore didn't even so much as mention her once. Literally all she got was her short blurb on the Universe page updated to briefly cover how some no-name Demacians view her.
Now that they've seemingly moved on from Demacia, does that mean Sona's basically stuck in lore limbo forever? I mean, they've repeatedly missed easy chances to update her, let her have some sort of interaction with someone... You could outright delete her from the game at this point and the lore would be entirely unaffected by her removal, which is absurd for a character affiliated with one of the biggest in-universe regions and who has abilities that said nation should consider taboo.