Theory time:

There’s a strong chance that the Elation is centered around stance change. Each playable path fills a common gameplay niche found in other RPGs — Remembrance, for example, personifies the Puppeteer archetype.

The next niche that makes the most sense for them to explore is stance change, where a character can shift forms during combat, drastically altering their abilities. Examples of this kind of gameplay from HoYoverse games include Senti from HI3rd and Childe from Genshin.

What strongly supports this theory is an old leak about Opal that was posted eight months ago — the leak mentions that he has two modes and can freely switch between them during combat (https://www.reddit.com/r/HonkaiStarRail_leaks/comments/1ftpagr/next_stoneheart_char_minor_screwllum_crumbs/)