SPOILERS FOR GENSHIN IMPACT 7.1 : A REKVIEM FOR THE UNDERWORLD Read at your own risk! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - After the battle, the Traveler and their companions emerged victorious and Ronova was "defeated", but after that battle, several days actually passed before we see Ronova in the cutscene at the very end. So although everyone may think that she is dead, I highly doubt it because of that. several days passed after the battle and even though Pierro dealt the 'final blow', Ronova was still up and at it for days after that. During that time, she went searching for the Eitr, otherwise known as the Embryonic-Ichoric-Telluric-Rudiment, which had been hidden in the shadow realm for a reason I can't remember. The Eitr was a product of Hyperborean research and experimentation, and contains the power of the light realm and the ability to alter the essence of life itself. Ronova found the orb of Eitr and fused it into the celestial nail somewhere in Snezhnaya, frozen in the air above the corpse of the Cryo Dragon Sovereign. People have theorised that since the Eitr wields the ability to alter the 'essence of life', the celestial nails could in fact be living things, or organic in a sense. A recorded entry of the effects of the Eitr stated that it forces organic matter to converge into a specific pattern. The pattern—or anomaly in this case—being the stars that began to appear above each celestial nail. These anomalies happened exactly above each celestial nail in the 6 nations: Mondstadt, Liyue, Inazuma, Sumeru, Natlan and Snezhnaya. The reason why Fontaine and Nod Krai do not have celestial nails is because those two nations never did anything that 'needed nailing' from the Heavenly Principles. The Heavenly Principles originally sent down those celestial nails whenever it saw fit which was whenever something happened in a nation that posed a threat to humanity or Teyvat as a whole. In Ronova's cutscene, plenty of information can be gained as to what she did and why she did it. She speaks of needing not to despise humans or gods any longer, as well as mentioning who I assume to be the Heavenly Principles, in blocked out text. This shows that the reason she did this is so the world can experience the same mortality or 'death' that she did. She also says, "Take this feeling with the hallowing of soil and give them to the world... this is my parting gift." To hallow means to make holy, and when speaking of hallowing and soil, she means the Holy Soil. The Holy Soil is soil containing a high concentration of primordial elemental energy from the primordial realms (e.g. the Light Realm), which allows dragons to thrive. But while being life-sustaining for elemental dragons, it also makes the land completely uninhabitable for humans. Referring back to the Heavenly Principle's reason for the celestial nails, it planted them to suppress the Holy Soil and dragon dominance in certain dense areas, and make Teyvat habitable for humans. So with this information, it can be inferred that Ronova's goal in fusing the Eitr into the celestial nail is to either cause another cataclysm on Teyvat (like Khaenri'ah) or revert Teyvat back to it's original form, where dragons and vishaps ruled. Either way, she wants everyone to experience death the way she did. Feel free to leave /constructive/ criticism on my analysis in the comments :]
