So you released short stories for Azir and Xerath. What about for Sivir, Cass, Ezreal, etc.?

It's been confirmed they're getting updated bios, at least.

As for full fledged short stories in addition to those, like Xerath/Azir are scheduled to get, I don't know. I guess it depends on the time Narrative has to work on them before they want to move on. New champ on the horizon is also probably being shunted to the front of the priority list.

Riot said they didn't actually write any of them for the Shurima event and then postponed them even further because of technical difficulties (pure bs btw, even i could write a HTML page with a large wall of text).