Technically speaking it's well possible for Genshin to get a collab character in 6.x and if so it's 100% going to be Sephiroth from the Final Fantasy series
>tall ikemen with a sword, all of which can be implemented with Genshin's assets
>the dev team openly said they adore Final Fantasy series in their Nod Krai livestream
>Final Fantasy is THE most iconic JRPG franchise, and is popular and 'normal' enough for a big mainstream normalfag like Genshin Impact
>Nod Krai in nature is a 'filler' region (not in a bad way) so giving a 5-star spot to a collab character wouldn't be a waste
The only mystery would be his supposed element but come the fuck on they gave Skirk Cryo