I bet a lot of players are thinking we'll need to kill Ronova, but I highly doubt it. Not only would it be a terrible idea from a marketing standpoint (I anticipate we're going to get a "Dark" element for Ronova and Dainsleif), but lore-wise it would also be really bad if Ronova was slain.

When Havria, Orobashi, and Decarabian died, they did not go gentle. Havria killed just about everyone in her city upon her death, and Orobashi and Decarabian essentially irradiated the areas where they died for centuries. Ronova eclipses all of them in power, so her being slain would, at bare minimum, likely kill everyone in an area the size of Snezhnograd, if not in a larger radius.

As such, if we're to get Ronova out of the way, we'll have to do something other than killing her.

EDIT: Looks like I was wrong; Pierro mortally wounds Ronova, but only after she's been stripped of her Authority of Death by the Heavenly Principles. But given she infused a Nail of Retribution with Eitr in her dying breath, she's clearly trying to take all of Teyvat with her.