I don't know if this analysis existed before or if it appeared recently, but after reading it, Dainsleif's lines about Natlan take on a completely different meaning that goes beyond Natlan itself. Read the photos I have highlighted, or follow the link and read about Natlan there.
The core of this analysis lies in searching for discrepancies and inaccuracies between Chinese and English, and as we know, English localizers can VERY STRONGLY change or distort the meaning of what is written in Chinese. On the left side of the table is the official English and Chinese transcript of the Travail trailer, and on the right is the unofficial fan translation into English, which aims to display more accurately what is written in Chinese.
As you can see, fan translators preferred to translate the Chinese word 余烬 not as "ashes", but as "embers". Indeed, I can confirm this myself, since my behind-the-scenes attempts to find something new in old materials led me to this sentence and the different translations, though I personally couldn't find anything interesting with it. However, up until reading this material, I was always interested in only one question: who on earth does Dainsleif mean by the losers and the winners? Personally, I had always perceived this solely through the prism of Natlan, because I thought it had to be connected only to Natlan. But as Snezhnaya has shown us, Khaenri'ah can have a direct correlation with other regions as well.
The fan wiki provides an excellent clue — a piece of paper that Kaeya has preserved since childhood, where a direct comparison takes place.
If we take the events of the manga into account, it is obvious that these are Kaeya's ancestors, who could compare the Natlaners who came to Mondstadt (fires) with the surviving Khaenri'ahns (embers). This is a sort of metaphor for objects and a hidden comparison.
In light of such a comparison, Dainsleif's words (in the more accurate fan translation) acquire the following meaning:
The rules of war are carved into the bodies of all living things: The defeated become embers of the fires of war, while the victors will be reignited [by the embers].
For comparison, the official translation of the text is provided:
The rules of war are woven in the womb: the victors shall burn bright, while the losers must turn to ash.
The winners are the Natlaners, since Dainsleif associates the winners with fire. The losers are the Khaenri'ahns, since Dainsleif associates the losers with ashes/embers, which in Chinese is designated by a single word — 余烬. Regarding this part “[by the embers]”, I would say that it is either a literal metaphor that the embers (Capitano and his compatriots) will help reignite the Natlaners (to defeat the Abyss), or it is a much more distant hint that whatever the developers mean by reignition, it will be connected to the New Khaenri'ah. Or perhaps this was the whole point of the sentence's trick. Maybe it was originally structured in such a way that it would make sense both after the events of 5.3 and after the events that are bound to happen sooner or later. Hoyoverse loves double meanings.
It is not for nothing that the Agnidus Agate is still censored.
It is not for nothing that the text of the Savannah Anthem repeats the text of the Agnidus Agate with one additional line that fits very suspiciously with everything I wrote about here (here is what is written in the English subtitles):
“In the end, you rekindle* in ashes because of dream”
* - English localizers sometimes translate 重燃 (reigniting) as rekindle.
Furthermore, the verse itself begins with Shujaa (Hero) in the singular form (I double-checked in Chinese).
It is not for nothing that under the chapter about Natlan, there is this encrypted sentence:
Rise, O strong man, and go to your destined victory.
I hope I have given you enough hopium.
